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NAME

       graph -  2D graph for plotting X-Y coordinate data.

SYNOPSIS

       graph pathName ?option value?...
_________________________________________________________________

DESCRIPTION

       The  graph command creates a graph for plotting two-dimensional data (X-Y coordinates). It
       has many configurable components: coordinate axes, elements,  legend,  grid  lines,  cross
       hairs, etc.  They allow you to customize the look and feel of the graph.

INTRODUCTION

       The   graph   command  creates  a  new  window  for  plotting  two-dimensional  data  (X-Y
       coordinates).  Data points are plotted in a rectangular area displayed in  the  center  of
       the  new window.  This is the plotting area.  The coordinate axes are drawn in the margins
       around the plotting area.  By default, the legend is displayed in the right  margin.   The
       title is displayed in top margin.

       The  graph  widget  is  composed  of  several  components: coordinate axes, data elements,
       legend, grid, cross hairs, pens, postscript, and annotation markers.

       axis      The graph has four standard axes (x, x2, y, and y2),  but  you  can  create  and
                 display  any  number of axes.  Axes control what region of data is displayed and
                 how the data is scaled. Each axis consists of the axis line,  title,  major  and
                 minor ticks, and tick labels.  Tick labels display the value at each major tick.

       crosshairs
                 Cross  hairs  are  used  to  position  the mouse pointer relative to the X and Y
                 coordinate axes. Two perpendicular lines, intersecting at the  current  location
                 of the mouse, extend across the plotting area to the coordinate axes.

       element   An  element  represents  a  set  of  data points. Elements can be plotted with a
                 symbol at each data point and lines connecting the points.   The  appearance  of
                 the element, such as its symbol, line width, and color is configurable.

       grid      Extends  the  major  and  minor  ticks  of  the  X-axis and/or Y-axis across the
                 plotting area.

       legend    The legend displays the name and symbol of each data element.  The legend can be
                 drawn in any margin or in the plotting area.

       marker    Markers  are  used  annotate  or  highlight areas of the graph. For example, you
                 could use a polygon marker to fill an area under a curve, or a  text  marker  to
                 label  a  particular  data  point.  Markers come in various forms: text strings,
                 bitmaps, connected line segments, images, polygons, or embedded widgets.

       pen       Pens define attributes (both symbol and line style) for elements.  Data elements
                 use  pens to specify how they should be drawn.  A data element may use many pens
                 at once.  Here, the particular pen used for a data point is determined from each
                 element's weight vector (see the element's -weight and -style options).

       postscript
                 The  widget  can  generate  encapsulated  PostScript  output. This component has
                 several options to configure how the PostScript is generated.

SYNTAX

       graph pathName ?option value?...  The graph command creates  a  new  window  pathName  and
       makes it into a graph widget.  At the time this command is invoked, there must not exist a
       window named pathName, but pathName's  parent  must  exist.   Additional  options  may  be
       specified  on the command line or in the option database to configure aspects of the graph
       such as its colors and font.  See the configure operation  below  for  the  exact  details
       about what option and value pairs are valid.

       If  successful,  graph  returns  the  path  name of the widget.  It also creates a new Tcl
       command by the same name.  You can use this command  to  invoke  various  operations  that
       query  or  modify  the  graph.   The  general  form  is: pathName operation ?arg?...  Both
       operation and its arguments determine the exact behavior of the command.   The  operations
       available for the graph are described in the GRAPH OPERATIONS section.

       The  command  can  also  be  used  to  access components of the graph.  pathName component
       operation ?arg?...  The operation, now located after the name of  the  component,  is  the
       function  to  be performed on that component. Each component has its own set of operations
       that manipulate that component.  They will be described below in their own sections.

EXAMPLE

       The graph command creates a new graph.

              # Create a new graph.  Plotting area is black.
              graph .g -plotbackground black

       A new Tcl command .g is also created.  This command can be used to query  and  modify  the
       graph.   For  example,  to  change  the  title  of the graph to "My Plot", you use the new
       command and the graph's configure operation.

              # Change the title.
              .g configure -title "My Plot"

       A graph has several components. To access a particular component you use  the  component's
       name.  For  example,  to  add  data  elements,  you  use  the  new command and the element
       component.

              # Create a new element named "line1"
              .g element create line1 \
                -xdata { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 } \
                -ydata { 26.18 50.46 72.85 93.31 111.86 128.47 143.14
                   155.85 166.60 175.38 }

       The element's X-Y coordinates are specified using  lists  of  numbers.   Alternately,  BLT
       vectors could be used to hold the X-Y coordinates.

              # Create two vectors and add them to the graph.
              vector xVec yVec
              xVec set { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 }
              yVec set { 26.18 50.46 72.85 93.31 111.86 128.47 143.14 155.85
                166.60 175.38 }
              .g element create line1 -xdata xVec -ydata yVec

       The  advantage  of  using  vectors is that when you modify one, the graph is automatically
       redrawn to reflect the new values.

              # Change the y coordinate of the first point.
              set yVector(0) 25.18

       An element named e1 is now created in .b.  It is automatically added to the  display  list
       of  elements.   You can use this list to control in what order elements are displayed.  To
       query or reset the element display list, you use the element's show operation.

              # Get the current display list
              set elemList [.b element show]
              # Remove the first element so it won't be displayed.
              .b element show [lrange $elemList 0 end]

       The element will be displayed by as many bars as there are data points (in this case there
       are ten).  The bars will be drawn centered at the x-coordinate of the data point.  All the
       bars will have the same attributes (colors, stipple, etc).  The width of each  bar  is  by
       default one unit.  You can change this with using the -barwidth option.

              # Change the X-Y coordinates of the first point.
              set xVec(0) 0.18
              set yVec(0) 25.18

       An  element  named  line1  is  now  created in .g.  By default, the element's label in the
       legend will be also line1.  You can change the label, or specify no  legend  entry,  again
       using the element's configure operation.

              # Don't display "line1" in the legend.
              .g element configure line1 -label ""

       You can configure more than just the element's label.  An element has many attributes such
       as symbol type and size, dashed or solid lines, colors, line width, etc.

              .g element configure line1 -symbol square -color red \
                -dashes { 2 4 2 } -linewidth 2 -pixels 2c

       Four coordinate axes are automatically created:  x,  x2,  y,  and  y2.   And  by  default,
       elements  are  mapped onto the axes x and y.  This can be changed with the -mapx and -mapy
       options.

              # Map "line1" on the alternate Y-axis "y2".
              .g element configure line1 -mapy y2

       Axes can be configured in many ways too.  For example, you change the scale of the  Y-axis
       from linear to log using the axis component.

              # Y-axis is log scale.
              .g axis configure y -logscale yes

       One  important  way  axes  are used is to zoom in on a particular data region.  Zooming is
       done by simply specifying new axis limits using the -min and -max configuration options.

              .g axis configure x -min 1.0 -max 1.5
              .g axis configure y -min 12.0 -max 55.15

       To zoom interactively, you link the axis configure operations with some  user  interaction
       (such  as  pressing  the mouse button), using the bind command.  To convert between screen
       and graph coordinates, use the invtransform operation.

              # Click the button to set a new minimum
              bind .g <ButtonPress-1> {
                  %W axis configure x -min [%W axis invtransform x %x]
                  %W axis configure x -min [%W axis invtransform x %y]
              }

       By default, the limits of the axis are determined from data values.  To reset back to  the
       default limits, set the -min and -max options to the empty value.

              # Reset the axes to autoscale again.
              .g axis configure x -min {} -max {}
              .g axis configure y -min {} -max {}

       By  default,  the  legend is drawn in the right margin.  You can change this or any legend
       configuration options using the legend component.

              # Configure the legend font, color, and relief
              .g legend configure -position left -relief raised \
                -font fixed -fg blue

       To prevent the legend from being displayed, turn on the -hide option.

              # Don't display the legend.
              .g legend configure -hide yes

       The graph widget has simple drawing procedures  called  markers.   They  can  be  used  to
       highlight  or  annotate  data  in  the  graph. The types of markers available are bitmaps,
       images, polygons, lines, or windows.  Markers can be used, for example, to mark  or  brush
       points.   In this example, is a text marker that labels the data first point.  Markers are
       created using the marker component.

              # Create a label for the first data point of "line1".
              .g marker create text -name first_marker -coords { 0.2 26.18 } \
                -text "start" -anchor se -xoffset -10 -yoffset -10

       This creates a text marker named first_marker.  It will display the text "start" near  the
       coordinates of the first data point.  The -anchor, -xoffset, and -yoffset options are used
       to display the marker above and to the left of the data point,  so  that  the  data  point
       isn't covered by the marker.  By default, markers are drawn last, on top of data.  You can
       change this with the -under option.

              # Draw the label before elements are drawn.
              .g marker configure first_marker -under yes

       You can add cross hairs or grid lines using the crosshairs and grid components.

              # Display both cross hairs and grid lines.
              .g crosshairs configure -hide no -color red
              .g grid configure -hide no -dashes { 2 2 }
              # Set up a binding to reposition the crosshairs.
              bind .g <Motion> {
                  .g crosshairs configure -position @%x,%y
              }

       The crosshairs are repositioned as the mouse pointer is moved in the graph.   The  pointer
       X-Y coordinates define the center of the crosshairs.

       Finally, to get hardcopy of the graph, use the postscript component.

              # Print the graph into file "file.ps"
              .g postscript output file.ps -maxpect yes -decorations no

       This  generates  a  file file.ps containing the encapsulated PostScript of the graph.  The
       option -maxpect says to scale the  plot  to  the  size  of  the  page.   Turning  off  the
       -decorations option denotes that no borders or color backgrounds should be drawn (i.e. the
       background of the margins, legend, and plotting area will be white).

GRAPH OPERATIONS

       pathName axis operation ?arg?...
              See the AXIS COMPONENTS section.

       pathName bar elemName ?option value?...
              Creates a new barchart element elemName.  It's an  error  if  an  element  elemName
              already  exists.   See  the  manual  for barchart for details about what option and
              value pairs are valid.

       pathName cget option
              Returns the current value of the configuration option given by option.  Option  may
              be any option described below for the configure operation.

       pathName configure ?option value?...
              Queries  or  modifies  the  configuration  options  of  the graph.  If option isn't
              specified, a list describing the current options  for  pathName  is  returned.   If
              option  is specified, but not value, then a list describing option is returned.  If
              one or more option and value pairs are specified, then for each  pair,  the  option
              option is set to value.  The following options are valid.

              -aspect width/height
                     Force a fixed aspect ratio of width/height, a floating point number.

              -background color
                     Sets the background color. This includes the margins and legend, but not the
                     plotting area.

              -borderwidth pixels
                     Sets the width of the 3-D border around the outside edge of the widget.  The
                     -relief option determines if the border is to be drawn.  The default is 2.

              -bottommargin pixels
                     If  non-zero,  overrides the computed size of the margin extending below the
                     X-coordinate axis.  If pixels is 0, the automatically computed size is used.
                     The default is 0.

              -bufferelements boolean
                     Indicates  whether an internal pixmap to buffer the display of data elements
                     should be used.  If boolean is true, data elements are drawn to an  internal
                     pixmap.   This  option  is  especially  useful  when  the  graph  is redrawn
                     frequently while the remains data unchanged (for example,  moving  a  marker
                     across the plot).  See the SPEED TIPS section.  The default is 1.

              -cursor cursor
                     Specifies the widget's cursor.  The default cursor is crosshair.

              -font fontName
                     Specifies  the  font  of the graph title. The default is *-Helvetica-Bold-R-
                     Normal-*-18-180-*.

              -halo pixels
                     Specifies a maximum distance to consider when searching for the closest data
                     point (see the element's closest operation below).  Data points further than
                     pixels away are ignored.  The default is 0.5i.

              -height pixels
                     Specifies the requested height of widget.  The default is 4i.

              -invertxy boolean
                     Indicates whether the placement X-axis and Y-axis should  be  inverted.   If
                     boolean is true, the X and Y axes are swapped.  The default is 0.

              -justify justify
                     Specifies  how  the  title  should be justified.  This matters only when the
                     title contains more than one line of text. Justify must be left,  right,  or
                     center.  The default is center.

              -leftmargin pixels
                     If  non-zero,  overrides  the computed size of the margin extending from the
                     left edge of the window to the Y-coordinate  axis.   If  pixels  is  0,  the
                     automatically computed size is used.  The default is 0.

              -plotbackground color
                     Specifies the background color of the plotting area.  The default is white.

              -plotborderwidth pixels
                     Sets  the width of the 3-D border around the plotting area.  The -plotrelief
                     option determines if a border is drawn.  The default is 2.

              -plotpadx pad
                     Sets the amount of padding to be added to the left and right  sides  of  the
                     plotting  area.   Pad  can be a list of one or two screen distances.  If pad
                     has two elements, the left side of the plotting area entry is padded by  the
                     first  distance  and  the  right  side  by  the  second.  If pad is just one
                     distance, both the left and right sides are padded evenly.  The  default  is
                     8.

              -plotpady pad
                     Sets the amount of padding to be added to the top and bottom of the plotting
                     area.  Pad can be a list of one or two screen distances.   If  pad  has  two
                     elements,  the  top of the plotting area is padded by the first distance and
                     the bottom by the second.  If pad is just one distance,  both  the  top  and
                     bottom are padded evenly.  The default is 8.

              -plotrelief relief
                     Specifies  the  3-D  effect for the plotting area.  Relief specifies how the
                     interior of the plotting area should appear relative to rest of  the  graph;
                     for example, raised means the plot should appear to protrude from the graph,
                     relative to the surface of the graph.  The default is sunken.

              -relief relief
                     Specifies the 3-D effect for the graph widget.   Relief  specifies  how  the
                     graph  should  appear  relative  to  widget  it is packed into; for example,
                     raised means the graph should appear to protrude.  The default is flat.

              -rightmargin pixels
                     If non-zero, overrides the computed size of the margin  extending  from  the
                     plotting  area  to  the  right edge of the window. By default, the legend is
                     drawn in this margin.  If pixels is 0, the automatically  computed  size  is
                     used.  The default is 0.

              -takefocus focus
                     Provides  information  used  when moving the focus from window to window via
                     keyboard traversal (e.g., Tab and Shift-Tab).  If focus  is  0,  this  means
                     that  this  window  should be skipped entirely during keyboard traversal.  1
                     means that the this window should always receive the input focus.  An  empty
                     value means that the traversal scripts make the decision whether to focus on
                     the window.  The default is "".

              -tile image
                     Specifies a tiled background  for  the  widget.   If  image  isn't  "",  the
                     background  is tiled using image.  Otherwise, the normal background color is
                     drawn (see the -background option).  Image must be an  image  created  using
                     the Tk image command.  The default is "".

              -title text
                     Sets the title to text. If text is "", no title will be displayed.

              -topmargin pixels
                     If  non-zero,  overrides  the computed size of the margin above the x2 axis.
                     If pixels is 0, the automatically computed size is used.  The default is 0.

              -width pixels
                     Specifies the requested width of the widget.  The default is 5i.

       pathName crosshairs operation ?arg?
              See the CROSSHAIRS COMPONENT section.

       pathName element operation ?arg?...
              See the ELEMENT COMPONENTS section.

       pathName extents item
              Returns the size  of  a  particular  item  in  the  graph.   Item  must  be  either
              leftmargin, rightmargin, topmargin, bottommargin, plotwidth, or plotheight.

       pathName grid operation ?arg?...
              See the GRID COMPONENT section.

       pathName invtransform winX winY
              Performs  an  inverse coordinate transformation, mapping window coordinates back to
              graph coordinates, using the  standard  X-axis  and  Y-axis.   Returns  a  list  of
              containing the X-Y graph coordinates.

       pathName inside x y
              Returns 1 is the designated screen coordinate (x and y) is inside the plotting area
              and 0 otherwise.

       pathName legend operation ?arg?...
              See the LEGEND COMPONENT section.

       pathName line operation arg...
              The operation is the same as element.

       pathName marker operation ?arg?...
              See the MARKER COMPONENTS section.

       pathName postscript operation ?arg?...
              See the POSTSCRIPT COMPONENT section.

       pathName snap ?switches? outputName
              Takes a snapshot of the graph, saving the  output  in  outputName.   The  following
              switches are available.

              -format format
                        Specifies  how the snapshot is output. Format may be one of the following
                        listed below.  The default is photo.

                        photo  Saves a Tk photo image. OutputName represents the  name  of  a  Tk
                               photo image that must already have been created.

                        wmf    Saves  an  Aldus  Placeable  Metafile.   OutputName represents the
                               filename  where  the  metafile  is  written.   If  outputName   is
                               CLIPBOARD,   then  output  is  written  directly  to  the  Windows
                               clipboard.  This format is available only under Microsoft Windows.

                        emf    Saves an Enhanced Metafile.  OutputName  represents  the  filename
                               where  the  metafile is written.  If outputName is CLIPBOARD, then
                               output is written directly to the Windows clipboard.  This  format
                               is available only under Microsoft Windows.

              -height size
                        Specifies the height of the graph.  Size is a screen distance.  The graph
                        will be redrawn using this dimension,  rather  than  its  current  window
                        height.

              -width size
                        Specifies  the width of the graph.  Size is a screen distance.  The graph
                        will be redrawn using this dimension,  rather  than  its  current  window
                        width.

       pathName transform x y
              Performs   a   coordinate  transformation,  mapping  graph  coordinates  to  window
              coordinates, using the standard X-axis and Y-axis.  Returns a list  containing  the
              X-Y screen coordinates.

       pathName xaxis operation ?arg?...

       pathName x2axis operation ?arg?...

       pathName yaxis operation ?arg?...

       pathName y2axis operation ?arg?...
              See the AXIS COMPONENTS section.

GRAPH COMPONENTS

       A  graph  is composed of several components: coordinate axes, data elements, legend, grid,
       cross hairs, postscript, and annotation markers. Instead of one big set  of  configuration
       options  and  operations,  the  graph  is  partitioned,  where  each component has its own
       configuration options and operations that specifically control that aspect or part of  the
       graph.

   AXIS COMPONENTS
       Four  coordinate  axes are automatically created: two X-coordinate axes (x and x2) and two
       Y-coordinate axes (y, and y2).  By default, the axis x is located in the bottom margin,  y
       in the left margin, x2 in the top margin, and y2 in the right margin.

       An  axis  consists of the axis line, title, major and minor ticks, and tick labels.  Major
       ticks are drawn at uniform intervals along the  axis.   Each  tick  is  labeled  with  its
       coordinate value.  Minor ticks are drawn at uniform intervals within major ticks.

       The  range  of  the axis controls what region of data is plotted.  Data points outside the
       minimum and maximum limits of the axis are not  plotted.   By  default,  the  minimum  and
       maximum limits are determined from the data, but you can reset either limit.

       You  can  have  several  axes. To create an axis, invoke the axis component and its create
       operation.

              # Create a new axis called "tempAxis"
              .g axis create tempAxis

       You map data elements to an  axis  using  the  element's  -mapy  and  -mapx  configuration
       options. They specify the coordinate axes an element is mapped onto.

              # Now map the tempAxis data to this axis.
              .g element create "e1" -xdata $x -ydata $y -mapy tempAxis

       Any  number  of  axes  can  be  displayed  simultaneously.  They  are drawn in the margins
       surrounding the plotting area.  The default axes x and y are drawn in the bottom and  left
       margins.  The axes x2 and y2 are drawn in top and right margins.  By default, only x and y
       are shown. Note that the axes can have different scales.

       To display a different axis or more than  one  axis,  you  invoke  one  of  the  following
       components:  xaxis,  yaxis,  x2axis,  and y2axis.  Each component has a use operation that
       designates the axis (or axes) to be drawn in  that  corresponding  margin:  xaxis  in  the
       bottom, yaxis in the left, x2axis in the top, and y2axis in the right.

              # Display the axis tempAxis in the left margin.
              .g yaxis use tempAxis

       The  use  operation  takes a list of axis names as its last argument.  This is the list of
       axes to be drawn in this margin.

       You can configure axes in many ways. The axis scale can be  linear  or  logarithmic.   The
       values  along  the axis can either monotonically increase or decrease.  If you need custom
       tick labels, you can specify a Tcl procedure to format the label any way  you  wish.   You
       can  control  how  ticks  are  drawn, by changing the major tick interval or the number of
       minor ticks.  You can define non-uniform tick intervals, such as for time-series plots.

       pathName axis bind tagName ?sequence?  ?command?
              Associates command with tagName such that whenever  the  event  sequence  given  by
              sequence  occurs for an axis with this tag, command will be invoked.  The syntax is
              similar to the bind command except that it operates  on  graph  axes,  rather  than
              widgets.  See  the  bind  manual  entry  for  complete  details on sequence and the
              substitutions performed on command before invoking it.

              If all arguments are specified  then  a  new  binding  is  created,  replacing  any
              existing  binding  for  the  same  sequence and tagName.  If the first character of
              command is + then command augments an existing binding rather  than  replacing  it.
              If  no  command  argument  is  provided  then the command currently associated with
              tagName and sequence (it's an error occurs if there's no such binding) is returned.
              If both command and sequence are missing then a list of all the event sequences for
              which bindings have been defined for tagName.

       pathName axis cget axisName option
              Returns the current value of the option given by option for axisName.   Option  may
              be any option described below for the axis configure operation.

       pathName axis configure axisName ?axisName?... ?option value?...
              Queries  or  modifies  the  configuration options of axisName.  Several axes can be
              changed.  If option isn't specified, a list describing all the current options  for
              axisName  is  returned.   If  option  is  specified,  but  not  value,  then a list
              describing option is  returned.   If  one  or  more  option  and  value  pairs  are
              specified,  then  for  each  pair,  the  axis  option  option is set to value.  The
              following options are valid for axes.

              -bindtags tagList
                     Specifies the binding tags for the axis.  TagList is a list of  binding  tag
                     names.   The  tags  and  their  order will determine how events for axes are
                     handled.  Each tag in the list matching the current event sequence will have
                     its  Tcl command executed.  Implicitly the name of the element is always the
                     first tag in the list.  The default value is all.

              -color color
                     Sets the color of the axis and tick labels.  The default is black.

              -command prefix
                     Specifies a Tcl command to be invoked when formatting the axis tick  labels.
                     Prefix is a string containing the name of a Tcl proc and any extra arguments
                     for the procedure.  This command is invoked for each major tick on the axis.
                     Two  additional  arguments  are passed to the procedure: the pathname of the
                     widget and the current the numeric value of the tick.  The procedure returns
                     the  formatted  tick label.  If "" is returned, no label will appear next to
                     the tick.  You can get the standard tick labels again by setting  prefix  to
                     "".  The default is "".

                     Please  note that this procedure is invoked while the graph is redrawn.  You
                     may query configuration options.  But do not them,  because  this  can  have
                     unexpected results.

              -descending boolean
                     Indicates  whether the values along the axis are monotonically increasing or
                     decreasing.  If boolean is true, the axis values will  be  decreasing.   The
                     default is 0.

              -hide boolean
                     Indicates  if  the  axis  is displayed. If boolean is false the axis will be
                     displayed. Any element mapped to the  axis  is  displayed  regardless.   The
                     default value is 0.

              -justify justify
                     Specifies  how  the  axis title should be justified.  This matters only when
                     the axis title contains more than one line of text. Justify  must  be  left,
                     right, or center.  The default is center.

              -limits formatStr
                     Specifies a printf-like description to format the minimum and maximum limits
                     of the axis.  The limits are displayed at the top/bottom or left/right sides
                     of   the  plotting  area.   FormatStr  is  a  list  of  one  or  two  format
                     descriptions.  If one description is supplied, both the minimum and  maximum
                     limits  are  formatted  in  the  same way.  If two, the first designates the
                     format for the minimum limit, the second for the maximum.  If "" is given as
                     either  description, then the that limit will not be displayed.  The default
                     is "".

              -linewidth pixels
                     Sets the width of the axis and tick lines.  The default is 1 pixel.

              -logscale boolean
                     Indicates whether the scale of  the  axis  is  logarithmic  or  linear.   If
                     boolean is true, the axis is logarithmic.  The default scale is linear.

              -loose boolean
                     Indicates whether the limits of the axis should fit the data points tightly,
                     at the outermost data points, or loosely, at the outer tick  intervals.   If
                     the  axis  limit is set with the -min or -max option, the axes are displayed
                     tightly.  If boolean is true, the axis range is "loose".  The default is 0.

              -majorticks majorList
                     Specifies where to display major axis ticks.  You can  use  this  option  to
                     display  ticks  at  non-uniform  intervals.   MajorList  is  a  list of axis
                     coordinates designating the location of major ticks.   No  minor  ticks  are
                     drawn.   If majorList is "", major ticks will be automatically computed. The
                     default is "".

              -max value
                     Sets the maximum limit of axisName.  Any data point greater  than  value  is
                     not  displayed.   If  value is "", the maximum limit is calculated using the
                     largest data value.  The default is "".

              -min value
                     Sets the minimum limit of axisName. Any data point less than  value  is  not
                     displayed.   If  value  is  "",  the  minimum  limit is calculated using the
                     smallest data value.  The default is "".

              -minorticks minorList
                     Specifies where to display minor axis ticks.  You can  use  this  option  to
                     display  minor  ticks  at non-uniform intervals. MinorList is a list of real
                     values, ranging from 0.0 to 1.0, designating the placement of a minor  tick.
                     No minor ticks are drawn if the -majortick option is also set.  If minorList
                     is "", minor ticks will be automatically computed. The default is "".

              -rotate theta
                     Specifies the how many degrees to rotate the axis tick labels.  Theta  is  a
                     real  value  representing  the  number of degrees to rotate the tick labels.
                     The default is 0.0 degrees.

              -scrollcommand command
                     Specify the prefix for a command used to  communicate  with  scrollbars  for
                     this axis, such as .sbar set.

              -scrollmax value
                     Sets  the  maximum  limit  of  the  axis scroll region.  If value is "", the
                     maximum limit is calculated using the largest data value.   The  default  is
                     "".

              -scrollmin value
                     Sets  the  minimum limit of axis scroll region.  If value is "", the minimum
                     limit is calculated using the smallest data value.  The default is "".

              -showticks boolean
                     Indicates whether axis ticks should be drawn. If boolean is true, ticks  are
                     drawn.  If false, only the axis line is drawn. The default is 1.

              -stepsize value
                     Specifies  the  interval  between  major axis ticks.  If value isn't a valid
                     interval (must be less than the axis range), the request is ignored and  the
                     step size is automatically calculated.

              -subdivisions number
                     Indicates how many minor axis ticks are to be drawn.  For example, if number
                     is two, only one minor tick is drawn.  If number is one, no minor ticks  are
                     displayed.  The default is 2.

              -tickfont fontName
                     Specifies  the  font  for axis tick labels. The default is *-Courier-Bold-R-
                     Normal-*-100-*.

              -ticklength pixels
                     Sets the length of major and minor ticks (minor ticks are half the length of
                     major  ticks).  If  pixels is less than zero, the axis will be inverted with
                     ticks drawn pointing towards the plot.  The default is 0.1i.

              -title text
                     Sets the title of the axis. If text is "", no axis title will be displayed.

              -titlealternate boolean
                     Indicates to display the axis title in its alternate location.  Normally the
                     axis  title  is centered along the axis.  This option places the axis either
                     to the right (horizontal axes) or  above  (vertical  axes)  the  axis.   The
                     default is 0.

              -titlecolor color
                     Sets the color of the axis title. The default is black.

              -titlefont fontName
                     Specifies  the  font  for  axis  title.  The  default is *-Helvetica-Bold-R-
                     Normal-*-14-140-*.

              Axis configuration options may be also be set by the option command.  The  resource
              class is Axis.  The resource names are the names of the axes (such as x or x2).

                     option add *Graph.Axis.Color  blue
                     option add *Graph.x.LogScale  true
                     option add *Graph.x2.LogScale false

       pathName axis create axisName ?option value?...
              Creates  a  new  axis  by  the name axisName.  No axis by the same name can already
              exist. Option and value are described in above in the axis configure operation.

       pathName axis delete ?axisName?...
              Deletes the named axes. An axis is not really deleted until it  is  not  longer  in
              use, so it's safe to delete axes mapped to elements.

       pathName axis invtransform axisName value
              Performs  the  inverse  transformation,  changing  the screen coordinate value to a
              graph coordinate,  mapping  the  value  mapped  to  axisName.   Returns  the  graph
              coordinate.

       pathName axis limits axisName
              Returns  a  list  of the minimum and maximum limits for axisName.  The order of the
              list is min max.

       pathName axis names ?pattern?...
              Returns a list of axes matching zero or more patterns.  If no pattern  argument  is
              give, the names of all axes are returned.

       pathName axis transform axisName value
              Transforms  the  coordinate  value  to  a  screen  coordinate  by mapping the it to
              axisName.  Returns the transformed screen coordinate.

       pathName axis view axisName
              Change the viewable area of  this  axis.  Use  as  an  argument  to  a  scrollbar's
              "-command".

       The  default  axes  are  x,  y,  x2,  and  y2.   But  you  can display more than four axes
       simultaneously.  You can also swap in a different axis with use operation of  the  special
       axis components: xaxis, x2axis, yaxis, and y2axis.

              .g create axis temp
              .g create axis time
              ...
              .g xaxis use temp
              .g yaxis use time

       Only the axes specified for use are displayed on the screen.

       The  xaxis, x2axis, yaxis, and y2axis components operate on an axis location rather than a
       specific axis like the more general axis component does.  They implicitly control the axis
       that  is  currently using to that location.  By default, xaxis uses the x axis, yaxis uses
       y, x2axis uses x2, and y2axis uses y2.  When more than one axis is displayed in a  margin,
       it represents the first axis displayed.

       The following operations are available for axes. They mirror exactly the operations of the
       axis component.  The axis argument must be xaxis, x2axis, yaxis, or y2axis.  This  feature
       is  deprecated since more than one axis can now be used a margin.  You should only use the
       xaxis, x2axis, yaxis, and y2axis  components  with  the  use  operation.   For  all  other
       operations, use the general axis component instead.

       pathName axis cget option

       pathName axis configure ?option value?...

       pathName axis invtransform value

       pathName axis limits

       pathName axis transform value

       pathName axis use ?axisName?
              Designates the axis axisName is to be displayed at this location.  AxisName can not
              be already in use at another location.  This command returns the name of  the  axis
              currently using this location.

   CROSSHAIRS COMPONENT
       Cross  hairs  consist  of  two  intersecting lines (one vertical and one horizontal) drawn
       completely across the plotting area.  They are used to position the mouse in  relation  to
       the  coordinate  axes.   Cross hairs differ from line markers in that they are implemented
       using XOR drawing primitives.  This means that  they  can  be  quickly  drawn  and  erased
       without  redrawing  the  entire  graph.   Note  that  crosshair  are  enabled  by  calling
       Blt_Crosshairs  and  turned  off   by   calling   Blt_ResetCrosshairs.    Similarly   call
       Blt_ZoomStack for zooming.

       The following operations are available for cross hairs:

       pathName crosshairs cget option
              Returns  the current value of the cross hairs configuration option given by option.
              Option may be any option described below for the cross hairs configure operation.

       pathName crosshairs configure ?option value?...
              Queries or modifies the configuration options of the cross hairs.  If option  isn't
              specified,  a  list  describing  all  the  current  options  for the cross hairs is
              returned.  If option is specified, but not value, then a list describing option  is
              returned.  If one or more option and value pairs are specified, then for each pair,
              the cross hairs option option is set to value.  The following options are available
              for cross hairs.

              -color color
                     Sets the color of the cross hairs.  The default is black.

              -dashes dashList
                     Sets  the  dash  style  of  the  cross hairs. DashList is a list of up to 11
                     numbers that alternately represent the lengths of the dashes and gaps on the
                     cross  hair  lines.   Each number must be between 1 and 255.  If dashList is
                     "", the cross hairs will be solid lines.

              -hide boolean
                     Indicates whether cross hairs are drawn. If boolean is true, cross hairs are
                     not drawn.  The default is yes.

              -linewidth pixels
                     Set the width of the cross hair lines.  The default is 1.

              -position pos
                     Specifies  the screen position where the cross hairs intersect.  Pos must be
                     in the form "@x,y", where  x  and  y  are  the  window  coordinates  of  the
                     intersection.

              Cross  hairs  configuration  options may be also be set by the option command.  The
              resource name and class are crosshairs and Crosshairs respectively.

                     option add *Graph.Crosshairs.LineWidth 2
                     option add *Graph.Crosshairs.Color     red

       pathName crosshairs off
              Turns off the cross hairs.

       pathName crosshairs on
              Turns on the display of the cross hairs.

       pathName crosshairs toggle
              Toggles the current state of the cross hairs, alternately mapping and unmapping the
              cross hairs.

   ELEMENT COMPONENTS
       A  data  element  represents  a  set  of data.  It contains x and y vectors containing the
       coordinates of the data points.  Elements can be displayed with  a  symbol  at  each  data
       point  and lines connecting the points.  Elements also control the appearance of the data,
       such as the symbol type, line width, color etc.

       When new data elements are created, they are automatically added to a  list  of  displayed
       elements.   The display list controls what elements are drawn and in what order.

       The following operations are available for elements.

       pathName element activate elemName ?index?...
              Specifies  the  data points of element elemName to be drawn using active foreground
              and background colors.  ElemName is the name of the element and index is  a  number
              representing  the  index of the data point. If no indices are present then all data
              points become active.

       pathName element bind tagName ?sequence?  ?command?
              Associates command with tagName such that whenever  the  event  sequence  given  by
              sequence  occurs for an element with this tag, command will be invoked.  The syntax
              is similar to the bind command except that it operates on  graph  elements,  rather
              than  widgets.  See  the bind manual entry for complete details on sequence and the
              substitutions performed on command before invoking it.

              If all arguments are specified  then  a  new  binding  is  created,  replacing  any
              existing  binding  for  the  same  sequence and tagName.  If the first character of
              command is + then command augments an existing binding rather  than  replacing  it.
              If  no  command  argument  is  provided  then the command currently associated with
              tagName and sequence (it's an error occurs if there's no such binding) is returned.
              If both command and sequence are missing then a list of all the event sequences for
              which bindings have been defined for tagName.

       pathName element cget elemName option
              Returns the current value of the element  configuration  option  given  by  option.
              Option  may  be  any  of  the  options  described  below  for the element configure
              operation.

       pathName element closest x y varName ?option value?... ?elemName?...

              Searches for the data point closest to the window coordinates x and y.  By default,
              all  elements  are  searched.   Hidden elements (see the -hide option is false) are
              ignored.  You can limit the search by specifying only the elements you want  to  be
              considered.   ElemName  must  be  the  name  of  an  element that is not be hidden.
              VarName is the name of a Tcl array variable and will contain  the  search  results:
              the name of the closest element, the index of the closest data point, and the graph
              coordinates of the point. Returns 0, if no data point within the threshold distance
              can  be  found,  otherwise  1  is  returned.   The following option-value pairs are
              available.

              -along direction
                     Search for the closest element using the following criteria:

                     x      Find closest element vertically from the given X-coordinate.

                     y      Find the closest element horizontally from the given Y-coordinate.

                     both   Find the closest element for the given point (using both the X and  Y
                            coordinates).

              -halo pixels
                     Specifies  a  threshold  distance  where  selected  data points are ignored.
                     Pixels is a valid screen distance, such as 2 or 1.2i.  If this option  isn't
                     specified, then it defaults to the value of the graph's -halo option.

              -interpolate string
                     Indicates  whether  to consider projections that lie along the line segments
                     connecting data points when searching for the closest  point.   The  default
                     value is 0. The values for string are described below.

                     no          Search only for the closest data point.

                     yes         Search  includes  projections  that  lie along the line segments
                                 connecting the data points.

       pathName element configure elemName ?elemName... ?option value?...
              Queries or modifies the configuration options for elements.  Several  elements  can
              be  modified at the same time. If option isn't specified, a list describing all the
              current options for elemName is returned.  If option is specified, but  not  value,
              then  a  list  describing the option option is returned.  If one or more option and
              value pairs are specified, then for each pair, the element option option is set  to
              value.  The following options are valid for elements.

              -activepen penName
                     Specifies  pen  to  use to draw active element.  If penName is "", no active
                     elements will be drawn.  The default is activeLine.

              -bindtags tagList
                     Specifies the binding tags for the element.  TagList is a  list  of  binding
                     tag  names.   The tags and their order will determine how events are handled
                     for elements.  Each tag in the list matching the current event sequence will
                     have its Tcl command executed.  Implicitly the name of the element is always
                     the first tag in the list.  The default value is all.

              -color color
                     Sets the color of the traces connecting the data points.

              -dashes dashList
                     Sets the dash style of element line. DashList is a list of up to 11  numbers
                     that alternately represent the lengths of the dashes and gaps on the element
                     line.  Each number must be between 1 and 255.  If dashList is "", the  lines
                     will be solid.

              -data coordList
                     Specifies  the  X-Y coordinates of the data.  CoordList is a list of numeric
                     expressions representing the X-Y coordinate pairs of each data point.

              -fill color
                     Sets the interior color of symbols.  If color is "", then  the  interior  of
                     the symbol is transparent.  If color is defcolor, then the color will be the
                     same as the -color option.  The default is defcolor.

              -hide boolean
                     Indicates whether the element is displayed.  The default is no.

              -label text
                     Sets the element's label in the legend.  If text is  "",  the  element  will
                     have no entry in the legend.  The default label is the element's name.

              -linewidth pixels
                     Sets the width of the connecting lines between data points.  If pixels is 0,
                     no connecting lines will be drawn between symbols.  The default is 0.

              -mapx xAxis
                     Selects the X-axis to map the element's X-coordinates onto.  XAxis  must  be
                     the name of an axis.  The default is x.

              -mapy yAxis
                     Selects  the  Y-axis to map the element's Y-coordinates onto.  YAxis must be
                     the name of an axis. The default is y.

              -offdash color
                     Sets the color of the stripes  when  traces  are  dashed  (see  the  -dashes
                     option).   If color is "", then the "off" pixels will represent gaps instead
                     of stripes.  If color is defcolor, then the color will be the  same  as  the
                     -color option.  The default is defcolor.

              -outline color
                     Sets  the  color or the outline around each symbol.  If color is "", then no
                     outline is drawn. If color is defcolor, then the color will be the  same  as
                     the -color option.  The default is defcolor.

              -pen penname
                     Set the pen to use for this element.

              -outlinewidth pixels
                     Sets  the  width  of  the outline bordering each symbol.  If pixels is 0, no
                     outline will be drawn. The default is 1.

              -pixels pixels
                     Sets the size of symbols.  If pixels is 0, no symbols will  be  drawn.   The
                     default is 0.125i.

              -scalesymbols boolean
                     If  boolean  is true, the size of the symbols drawn for elemName will change
                     with scale of the X-axis and Y-axis.  At the time this option  is  set,  the
                     current  ranges  of  the  axes are saved as the normalized scales (i.e scale
                     factor is 1.0) and the element is drawn at  its  designated  size  (see  the
                     -pixels option).  As the scale of the axes change, the symbol will be scaled
                     according to the smaller of the X-axis and Y-axis  scales.   If  boolean  is
                     false, the element's symbols are drawn at the designated size, regardless of
                     axis scales.  The default is 0.

              -smooth smooth
                     Specifies how connecting  line  segments  are  drawn  between  data  points.
                     Smooth  can  be  either  linear,  step, natural, or quadratic.  If smooth is
                     linear, a single line segment is drawn, connecting both  data  points.  When
                     smooth  is step, two line segments are drawn. The first is a horizontal line
                     segment that steps the next X-coordinate.  The second is  a  vertical  line,
                     moving  to  the  next  Y-coordinate.   Both  natural  and quadratic generate
                     multiple segments  between  data  points.   If  natural,  the  segments  are
                     generated  using  a cubic spline.  If quadratic, a quadratic spline is used.
                     The default is linear.

              -styles styleList
                     Specifies what pen to use based on the range of weights given.  StyleList is
                     a list of style specifications. Each style specification, in turn, is a list
                     consisting of a pen name, and optionally a minimum and maximum range.   Data
                     points  whose weight (see the -weight option) falls in this range, are drawn
                     with this pen.  If no range is specified it defaults to the index of the pen
                     in   the  list.   Note  that  this  affects  only  symbol  attributes.  Line
                     attributes, such as line width, dashes, etc. are ignored.

              -symbol symbol
                     Specifies the symbol for data points.  Symbol can be either square,  circle,
                     diamond,  plus,  cross,  splus,  scross,  triangle,  ""  (where no symbol is
                     drawn), or a bitmap.  Bitmaps are specified as "source ?mask?", where source
                     is  the  name  of  the  bitmap, and mask is the bitmap's optional mask.  The
                     default is circle.

              -trace direction
                     Indicates whether connecting lines between data points  (whose  X-coordinate
                     values  are  either  increasing or decreasing) are drawn.  Direction must be
                     increasing, decreasing, or both.  For example, if direction  is  increasing,
                     connecting  lines  will  be  drawn  only  between  those  data  points where
                     X-coordinate values are monotonically increasing.   If  direction  is  both,
                     connecting lines will be draw between all data points.  The default is both.

              -weights wVec
                     Specifies  the  weights  of the individual data points.  This, with the list
                     pen styles (see the -styles option), controls how  data  points  are  drawn.
                     WVec  is  the  name  of  a  BLT  vector  or  a  list  of numeric expressions
                     representing the weights for each data point.

              -xdata xVec
                     Specifies the X-coordinates of the data.  XVec is the name of a  BLT  vector
                     or a list of numeric expressions.

              -ydata yVec
                     Specifies  the  Y-coordinates of the data.  YVec is the name of a BLT vector
                     or a list of numeric expressions.

              Element configuration options may also be set by the option command.  The  resource
              class is Element. The resource name is the name of the element.

                     option add *Graph.Element.symbol line
                     option add *Graph.e1.symbol line

       pathName element create elemName ?option value?...
              Creates  a  new  element  elemName.   It's  an error is an element elemName already
              exists.  If additional arguments are present, they specify options  valid  for  the
              element configure operation.

       pathName element deactivate elemName ?elemName?...
              Deactivates  all  the elements matching pattern.  Elements whose names match any of
              the patterns given are redrawn using their normal colors.

       pathName element delete ?elemName?...
              Deletes all the named elements.  The graph is automatically redrawn.

       pathName element exists elemName
              Returns 1 if an element elemName currently exists and 0 otherwise.

       pathName element names ?pattern?...
              Returns the elements matching one or more pattern.  If no  pattern  is  given,  the
              names of all elements is returned.

       pathName element show ?nameList?
              Queries  or modifies the element display list.  The element display list designates
              the elements drawn and in what  order.  NameList  is  a  list  of  elements  to  be
              displayed  in  the  order  they  are  named.  If there is no nameList argument, the
              current display list is returned.

       pathName element type elemName
              Returns the type of elemName.  If the  element  is  a  bar  element,  the  commands
              returns the string "bar", otherwise it returns "line".

   GRID COMPONENT
       Grid  lines  extend from the major and minor ticks of each axis horizontally or vertically
       across the plotting area.  The following operations are available for grid lines.

       pathName grid cget option
              Returns the current value of the grid line configuration option  given  by  option.
              Option may be any option described below for the grid configure operation.

       pathName grid configure ?option value?...
              Queries  or  modifies  the  configuration  options for grid lines.  If option isn't
              specified, a list describing all the current grid options for pathName is returned.
              If  option  is specified, but not value, then a list describing option is returned.
              If one or more option and value pairs are specified, then for each pair,  the  grid
              line  option  option  is  set  to  value.  The following options are valid for grid
              lines.

              -color color
                     Sets the color of the grid lines.  The default is black.

              -dashes dashList
                     Sets the dash style of the grid lines. DashList  is  a  list  of  up  to  11
                     numbers that alternately represent the lengths of the dashes and gaps on the
                     grid lines.  Each number must be between 1 and 255.  If dashList is "",  the
                     grid will be solid lines.

              -hide boolean
                     Indicates  whether  the grid should be drawn. If boolean is true, grid lines
                     are not shown. The default is yes.

              -linewidth pixels
                     Sets the width of grid lines.  The default width is 1.

              -mapx xAxis
                     Specifies the X-axis to display grid lines.  XAxis must be the  name  of  an
                     axis or "" for no grid lines.  The default is "".

              -mapy yAxis
                     Specifies  the  Y-axis  to display grid lines.  YAxis must be the name of an
                     axis or "" for no grid lines.  The default is y.

              -minor boolean
                     Indicates whether the grid lines  should  be  drawn  for  minor  ticks.   If
                     boolean is true, the lines will appear at minor tick intervals.  The default
                     is 1.

              Grid configuration options may also be set by the  option  command.   The  resource
              name and class are grid and Grid respectively.

                     option add *Graph.grid.LineWidth 2
                     option add *Graph.Grid.Color     black

              -raised boolean
                     Grid is to be raised or drawn over elements.

       pathName grid off
              Turns off the display the grid lines.

       pathName grid on
              Turns on the display the grid lines.

       pathName grid toggle
              Toggles the display of the grid.

   LEGEND COMPONENT
       The  legend  displays  a  list of the data elements.  Each entry consists of the element's
       symbol and label.  The legend can appear in any margin (the default  location  is  in  the
       right margin).  It can also be positioned anywhere within the plotting area.

       The following operations are valid for the legend.

       pathName legend activate pattern...
              Selects  legend entries to be drawn using the active legend colors and relief.  All
              entries whose element names match pattern   are  selected.   To  be  selected,  the
              element name must match only one pattern.

       pathName legend bind tagName ?sequence?  ?command?
              Associates  command  with  tagName  such  that whenever the event sequence given by
              sequence occurs for a  legend  entry  with  this  tag,  command  will  be  invoked.
              Implicitly  the  element names in the entry are tags.  The syntax is similar to the
              bind command except that it operates on legend entries, rather  than  widgets.  See
              the  bind  manual  entry  for  complete  details  on sequence and the substitutions
              performed on command before invoking it.

              If all arguments are specified  then  a  new  binding  is  created,  replacing  any
              existing  binding  for  the  same  sequence and tagName.  If the first character of
              command is + then command augments an existing binding rather  than  replacing  it.
              If  no  command  argument  is  provided  then the command currently associated with
              tagName and sequence (it's an error occurs if there's no such binding) is returned.
              If both command and sequence are missing then a list of all the event sequences for
              which bindings have been defined for tagName.

       pathName legend cget option
              Returns the current value of a legend configuration  option.   Option  may  be  any
              option described below in the legend configure operation.

       pathName legend configure ?option value?...
              Queries  or  modifies  the  configuration  options for the legend.  If option isn't
              specified, a list describing the current legend options for pathName  is  returned.
              If  option  is specified, but not value, then a list describing option is returned.
              If one or more option and value pairs are specified, then for each pair, the legend
              option option is set to value.  The following options are valid for the legend.

              -activebackground color
                     Sets  the  background  color  for active legend entries.  All legend entries
                     marked active (see the legend  activate  operation)  are  drawn  using  this
                     background color.

              -activeborderwidth pixels
                     Sets  the  width  of  the  3-D  border around the outside edge of the active
                     legend entries.  The default is 2.

              -activeforeground color
                     Sets the foreground color for active legend  entries.   All  legend  entries
                     marked  as  active  (see the legend activate operation) are drawn using this
                     foreground color.

              -activerelief relief
                     Specifies the 3-D effect desired for active legend entries.  Relief  denotes
                     how  the  interior  of  the  entry should appear relative to the legend; for
                     example, raised means the entry should appear to protrude from  the  legend,
                     relative to the surface of the legend.  The default is flat.

              -anchor anchor
                     Tells  how  to position the legend relative to the positioning point for the
                     legend.  This is dependent on  the  value  of  the  -position  option.   The
                     default is center.

                     left or right
                                 The anchor describes how to position the legend vertically.

                     top or bottom
                                 The anchor describes how to position the legend horizontally.

                     @x,y        The  anchor specifies how to position the legend relative to the
                                 positioning point. For example, if anchor  is  center  then  the
                                 legend  is centered on the point; if anchor is n then the legend
                                 will be drawn such that the top center point of the  rectangular
                                 region occupied by the legend will be at the positioning point.

                     plotarea    The  anchor specifies how to position the legend relative to the
                                 plotting area. For example, if anchor is center then the  legend
                                 is  centered  in  the  plotting  area;  if anchor is ne then the
                                 legend will be drawn such that occupies the upper  right  corner
                                 of the plotting area.

              -background color
                     Sets  the  background  color  of  the  legend.  If  color  is "", the legend
                     background with be transparent.

              -bindtags tagList
                     Specifies the binding tags for legend entries.  TagList is a list of binding
                     tag  names.   The tags and their order will determine how events are handled
                     for legend entries.  Each  tag  in  the  list  matching  the  current  event
                     sequence will have its Tcl command executed. The default value is all.

              -borderwidth pixels
                     Sets  the  width of the 3-D border around the outside edge of the legend (if
                     such border is being drawn; the relief option determines this).  The default
                     is 2 pixels.

              -font fontName
                     FontName  specifies  a  font  to use when drawing the labels of each element
                     into the legend.  The default is *-Helvetica-Bold-R-Normal-*-12-120-*.

              -foreground color
                     Sets the foreground color of the text drawn for the  element's  label.   The
                     default is black.

              -hide boolean
                     Indicates  whether  the  legend should be displayed. If boolean is true, the
                     legend will not be draw.  The default is no.

              -ipadx pad
                     Sets the amount of internal padding to be added to the width of each  legend
                     entry.   Pad  can  be a list of one or two screen distances.  If pad has two
                     elements, the left side of the legend entry is padded by the first  distance
                     and  the  right  side  by the second.  If pad is just one distance, both the
                     left and right sides are padded evenly.  The default is 2.

              -ipady pad
                     Sets an amount of internal padding to be added to the height of each  legend
                     entry.   Pad  can  be a list of one or two screen distances.  If pad has two
                     elements, the top of the entry is padded  by  the  first  distance  and  the
                     bottom  by the second.  If pad is just one distance, both the top and bottom
                     of the entry are padded evenly.  The default is 2.

              -padx pad
                     Sets the padding to the left and right exteriors of the legend.  Pad can  be
                     a  list  of  one or two screen distances.  If pad has two elements, the left
                     side of the legend is padded by the first distance and the right side by the
                     second.   If  pad  has  just one distance, both the left and right sides are
                     padded evenly.  The default is 4.

              -pady pad
                     Sets the padding above and below the legend.  Pad can be a list  of  one  or
                     two screen distances.  If pad has two elements, the area above the legend is
                     padded by the first distance and the area below by the second.   If  pad  is
                     just  one  distance,  both  the top and bottom areas are padded evenly.  The
                     default is 0.

              -position pos
                     Specifies where the legend is drawn. The -anchor option also  affects  where
                     the  legend is positioned.  If pos is left, left, top, or bottom, the legend
                     is drawn in the specified margin.  If pos is plotarea, then  the  legend  is
                     drawn  inside  the  plotting  area at a particular anchor.  If pos is in the
                     form "@x,y", where x and y are the window coordinates, the legend  is  drawn
                     in the plotting area at the specified coordinates.  The default is right.

              -raised boolean
                     Indicates  whether  the  legend  is  above or below the data elements.  This
                     matters only if the legend is in the plotting area.  If boolean is true, the
                     legend will be drawn on top of any elements that may overlap it. The default
                     is no.

              -relief relief
                     Specifies the 3-D effect for the border around the legend.  Relief specifies
                     how  the  interior  of  the  legend should appear relative to the graph; for
                     example, raised means the legend should appear to protrude from  the  graph,
                     relative to the surface of the graph.  The default is sunken.

              Legend  configuration  options may also be set by the option command.  The resource
              name and class are legend and Legend respectively.

                     option add *Graph.legend.Foreground blue
                     option add *Graph.Legend.Relief     raised

       pathName legend deactivate pattern...
              Selects legend entries to be drawn using the normal legend colors and relief.   All
              entries  whose  element  names  match  pattern  are  selected.  To be selected, the
              element name must match only one pattern.

       pathName legend get pos
              Returns the name of the element whose entry is at the screen position  pos  in  the
              legend.   Pos must be in the form "@x,y", where x and y are window coordinates.  If
              the given coordinates do not lie over a legend entry, "" is returned.

   PEN COMPONENTS
       Pens define attributes (both symbol  and  line  style)  for  elements.   Pens  mirror  the
       configuration  options  of  data elements that pertain to how symbols and lines are drawn.
       Data elements use pens to determine how they are drawn.  A data element  may  use  several
       pens  at  once.  In this case, the pen used for a particular data point is determined from
       each element's weight vector (see the element's -weight and -style options).

       One pen, called activeLine, is automatically created.  It's used as the default active pen
       for  elements.  So  you  can  change  the  active  attributes  for  all elements by simply
       reconfiguring this pen.

              .g pen configure "activeLine" -color green

       You can create and use several pens. To create a pen, invoke the  pen  component  and  its
       create operation.

              .g pen create myPen

       You map pens to a data element using either the element's -pen or -activepen options.

              .g element create "line1" -xdata $x -ydata $tempData \
                  -pen myPen

       An element can use several pens at once. This is done by specifying the name of the pen in
       the element's style list (see the -styles option).

              .g element configure "line1" -styles { myPen 2.0 3.0 }

       This says that any data point with a weight between 2.0 and 3.0 is to be drawn  using  the
       pen myPen.  All other points are drawn with the element's default attributes.

       The following operations are available for pen components.

       pathName pen cget penName option
              Returns the current value of the option given by option for penName.  Option may be
              any option described below for the pen configure operation.

       pathName pen configure penName ?penName... ?option value?...
              Queries or modifies the configuration options  of  penName.  Several  pens  can  be
              modified at once.  If option isn't specified, a list describing the current options
              for penName is returned.  If option is  specified,  but  not  value,  then  a  list
              describing  option  is  returned.   If  one  or  more  option  and  value pairs are
              specified, then for each pair,  the  pen  option  option  is  set  to  value.   The
              following options are valid for pens.

              -color color
                     Sets the color of the traces connecting the data points.

              -dashes dashList
                     Sets  the dash style of element line. DashList is a list of up to 11 numbers
                     that alternately represent the lengths of the dashes and gaps on the element
                     line.   Each number must be between 1 and 255.  If dashList is "", the lines
                     will be solid.

              -fill color
                     Sets the interior color of symbols.  If color is "", then  the  interior  of
                     the symbol is transparent.  If color is defcolor, then the color will be the
                     same as the -color option.  The default is defcolor.

              -linewidth pixels
                     Sets the width of the connecting lines between data points.  If pixels is 0,
                     no connecting lines will be drawn between symbols.  The default is 0.

              -offdash color
                     Sets  the  color  of  the  stripes  when  traces are dashed (see the -dashes
                     option).  If color is "", then the "off" pixels will represent gaps  instead
                     of  stripes.   If  color is defcolor, then the color will be the same as the
                     -color option.  The default is defcolor.

              -outline color
                     Sets the color or the outline around each symbol.  If color is "",  then  no
                     outline  is  drawn. If color is defcolor, then the color will be the same as
                     the -color option.  The default is defcolor.

              -outlinewidth pixels
                     Sets the width of the outline bordering each symbol.  If  pixels  is  0,  no
                     outline will be drawn. The default is 1.

              -pixels pixels
                     Sets  the  size  of symbols.  If pixels is 0, no symbols will be drawn.  The
                     default is 0.125i.

              -symbol symbol
                     Specifies the symbol for data points.  Symbol can be either square,  circle,
                     diamond,  plus,  cross,  splus,  scross,  triangle,  ""  (where no symbol is
                     drawn), or a bitmap.  Bitmaps are specified as "source ?mask?", where source
                     is  the  name  of  the  bitmap, and mask is the bitmap's optional mask.  The
                     default is circle.

              -type elemType
                     Specifies the type of element the pen is  to  be  used  with.   This  option
                     should  only be employed when creating the pen.  This is for those that wish
                     to mix different types of elements (bars and lines) on the same graph.   The
                     default type is "line".

              Pen  configuration  options may be also be set by the option command.  The resource
              class is Pen.  The resource names are the names of the pens.

                     option add *Graph.Pen.Color  blue
                     option add *Graph.activeLine.color  green

       pathName pen create penName ?option value?...
              Creates a new pen by the name penName.  No pen by the same name can already  exist.
              Option and value are described in above in the pen configure operation.

       pathName pen delete ?penName?...
              Deletes  the named pens. A pen is not really deleted until it is not longer in use,
              so it's safe to delete pens mapped to elements.

       pathName pen names ?pattern?...
              Returns a list of pens matching zero or more patterns.  If no pattern  argument  is
              give, the names of all pens are returned.

   POSTSCRIPT COMPONENT
       The  graph  can  generate encapsulated PostScript output.  There are several configuration
       options you can specify to control how the plot will be generated.   You  can  change  the
       page  dimensions  and  borders.   The  plot  itself can be scaled, centered, or rotated to
       landscape.  The PostScript output can be written directly to a file  or  returned  through
       the interpreter.

       The following postscript operations are available.

       pathName postscript cget option
              Returns  the current value of the postscript option given by option.  Option may be
              any option described below for the postscript configure operation.

       pathName postscript configure ?option value?...
              Queries or modifies the configuration options for PostScript generation.  If option
              isn't  specified,  a list describing the current postscript options for pathName is
              returned.  If option is specified, but not value, then a list describing option  is
              returned.  If one or more option and value pairs are specified, then for each pair,
              the postscript option option is set to value.  The following postscript options are
              available.

              -center boolean
                     Indicates  whether  the  plot should be centered on the PostScript page.  If
                     boolean is false, the plot will be placed in the upper left  corner  of  the
                     page.  The default is 1.

              -colormap varName
                     VarName  must  be the name of a global array variable that specifies a color
                     mapping from the X color name to PostScript.  Each element of  varName  must
                     consist  of  PostScript code to set a particular color value (e.g. ``1.0 1.0
                     0.0 setrgbcolor'').  When generating color information  in  PostScript,  the
                     array  variable  varName  is  checked if an element of the name as the color
                     exists. If so, it uses its value as the PostScript command to set the color.
                     If  this option hasn't been specified, or if there isn't an entry in varName
                     for a given color, then it uses the red, green, and  blue  intensities  from
                     the X color.

              -colormode mode
                     Specifies  how  to output color information.  Mode must be either color (for
                     full  color  output),  gray  (convert  all  colors   to   their   gray-scale
                     equivalents)  or  mono  (convert  foreground  colors to black and background
                     colors to white).  The default mode is color.

              -fontmap varName
                     VarName must be the name of a global array variable that  specifies  a  font
                     mapping  from  the  X font name to PostScript.  Each element of varName must
                     consist of a Tcl list with one or two elements; the name and point size of a
                     PostScript font.  When outputting PostScript commands for a particular font,
                     the array variable varName is checked to see if an element by the  specified
                     font  exists.   If  there  is  such  an  element,  then the font information
                     contained in that element is used in the PostScript output.  (If  the  point
                     size  is  omitted  from  the  list,  the  point size of the X font is used).
                     Otherwise the X font is examined in an attempt to guess what PostScript font
                     to  use.  This works only for fonts whose foundry property is Adobe (such as
                     Times, Helvetica, Courier, etc.).  If  all  of  this  fails  then  the  font
                     defaults to Helvetica-Bold.

              -decorations boolean
                     Indicates  whether PostScript commands to generate color backgrounds and 3-D
                     borders will be output.  If boolean is false, the background will  be  white
                     and no 3-D borders will be generated. The default is 1.

              -height pixels
                     Sets  the  height  of the plot.  This lets you print the graph with a height
                     different from the one drawn on the screen.  If pixels is 0, the  height  is
                     the same as the widget's height.  The default is 0.

              -landscape boolean
                     If  boolean  is  true,  this  specifies the printed area is to be rotated 90
                     degrees.  In non-rotated output the X-axis of the printed  area  runs  along
                     the  short  dimension  of  the  page  (``portrait'' orientation); in rotated
                     output the X-axis runs along the long dimension of the  page  (``landscape''
                     orientation).  Defaults to 0.

              -maxpect boolean
                     Indicates  to  scale  the  plot  so  that it fills the PostScript page.  The
                     aspect ratio of the graph is still retained.  The default is 0.

              -padx pad
                     Sets the horizontal padding for  the  left  and  right  page  borders.   The
                     borders  are  exterior  to the plot.  Pad can be a list of one or two screen
                     distances.  If pad has two elements, the left border is padded by the  first
                     distance  and the right border by the second.  If pad has just one distance,
                     both the left and right borders are padded evenly.  The default is 1i.

              -pady pad
                     Sets the vertical padding for the top and bottom page borders.  The  borders
                     are exterior to the plot.  Pad can be a list of one or two screen distances.
                     If pad has two elements, the top border is padded by the first distance  and
                     the bottom border by the second.  If pad has just one distance, both the top
                     and bottom borders are padded evenly.  The default is 1i.

              -paperheight pixels
                     Sets the height of the postscript page.  This can be used to select  between
                     different page sizes (letter, A4, etc).  The default height is 11.0i.

              -paperwidth pixels
                     Sets  the  width of the postscript page.  This can be used to select between
                     different page sizes (letter, A4, etc).  The default width is 8.5i.

              -width pixels
                     Sets the width of the plot.  This lets  you  generate  a  plot  of  a  width
                     different from that of the widget.  If pixels is 0, the width is the same as
                     the widget's width.  The default is 0.

              Postscript configuration options may be also be set by  the  option  command.   The
              resource name and class are postscript and Postscript respectively.

                     option add *Graph.postscript.Decorations false
                     option add *Graph.Postscript.Landscape   true

       pathName postscript output ?fileName? ?option value?...
              Outputs  a  file of encapsulated PostScript.  If a fileName argument isn't present,
              the command returns the PostScript. If any option-value pairs are present, they set
              configuration  options  controlling  how  the  PostScript is generated.  Option and
              value can be anything accepted by the postscript configure operation above.

   MARKER COMPONENTS
       Markers are simple drawing procedures used to annotate or highlight areas  of  the  graph.
       Markers  have  various  types: text strings, bitmaps, images, connected lines, windows, or
       polygons.  They can be associated with a particular element, so that when the  element  is
       hidden  or  un-hidden, so is the marker.  By default, markers are the last items drawn, so
       that data elements will appear in behind them.  You can change  this  by  configuring  the
       -under option.

       Markers,  in  contrast to elements, don't affect the scaling of the coordinate axes.  They
       can also have elastic coordinates (specified by -Inf and Inf respectively) that  translate
       into  the minimum or maximum limit of the axis.  For example, you can place a marker so it
       always remains in the lower left corner of the plotting area,  by  using  the  coordinates
       -Inf,-Inf.

       The following operations are available for markers.

       pathName marker after markerId ?afterId?
              Changes the order of the markers, drawing the first marker after the second.  If no
              second afterId argument is specified, the marker  is  placed  at  the  end  of  the
              display  list.  This command can be used to control how markers are displayed since
              markers are drawn in the order of this display list.

       pathName marker before markerId ?beforeId?
              Changes the order of the markers, drawing the first marker before the  second.   If
              no  second beforeId argument is specified, the marker is placed at the beginning of
              the display list.  This command can be used to control how  markers  are  displayed
              since markers are drawn in the order of this display list.

       pathName marker bind tagName ?sequence?  ?command?
              Associates  command  with  tagName  such  that whenever the event sequence given by
              sequence occurs for a marker with this tag, command will be invoked.  The syntax is
              similar  to  the bind command except that it operates on graph markers, rather than
              widgets. See the bind manual  entry  for  complete  details  on  sequence  and  the
              substitutions performed on command before invoking it.

              If  all  arguments  are  specified  then  a  new  binding is created, replacing any
              existing binding for the same sequence and tagName.   If  the  first  character  of
              command  is  +  then command augments an existing binding rather than replacing it.
              If no command argument is provided  then  the  command  currently  associated  with
              tagName and sequence (it's an error occurs if there's no such binding) is returned.
              If both command and sequence are missing then a list of all the event sequences for
              which bindings have been defined for tagName.

       pathName marker cget option
              Returns  the  current  value  of  the  marker configuration option given by option.
              Option may be any option described below in the configure operation.

       pathName marker configure markerId ?option value?...
              Queries or modifies  the  configuration  options  for  markers.   If  option  isn't
              specified,  a  list  describing  the  current options for markerId is returned.  If
              option is specified, but not value, then a list describing option is returned.   If
              one  or  more  option and value pairs are specified, then for each pair, the marker
              option option is set to value.

              The following options are valid for all markers.  Each type of marker also has  its
              own type-specific options.  They are described in the sections below.

              -bindtags tagList
                     Specifies the binding tags for the marker.  TagList is a list of binding tag
                     names.  The tags and their order will determine how events for  markers  are
                     handled.  Each tag in the list matching the current event sequence will have
                     its Tcl command executed.  Implicitly the name of the marker is  always  the
                     first tag in the list.  The default value is all.

              -coords coordList
                     Specifies  the  coordinates  of  the  marker.   CoordList is a list of graph
                     coordinates.  The number of coordinates required is dependent on the type of
                     marker.   Text,  image, and window markers need only two coordinates (an X-Y
                     coordinate).   Bitmap markers can take either two or  four  coordinates  (if
                     four,  they represent the corners of the bitmap). Line markers need at least
                     four coordinates, polygons at least six.  If coordList  is  "",  the  marker
                     will not be displayed.  The default is "".

              -element elemName
                     Links the marker with the element elemName.  The marker is drawn only if the
                     element is also currently displayed (see the element's show operation).   If
                     elemName is "", the marker is always drawn.  The default is "".

              -hide boolean
                     Indicates whether the marker is drawn. If boolean is true, the marker is not
                     drawn.  The default is no.

              -mapx xAxis
                     Specifies the X-axis to map the marker's X-coordinates onto.  XAxis must the
                     name of an axis.  The default is x.

              -mapy yAxis
                     Specifies the Y-axis to map the marker's Y-coordinates onto.  YAxis must the
                     name of an axis.  The default is y.

              -name markerId
                     Changes the identifier for the marker.   The  identifier  markerId  can  not
                     already  be  used  by  another  marker.  If this option isn't specified, the
                     marker's name is uniquely generated.

              -under boolean
                     Indicates whether the marker is drawn below/above data elements.  If boolean
                     is  true,  the  marker  is  be drawn underneath the data element symbols and
                     lines.  Otherwise, the marker is drawn on top of the element.   The  default
                     is 0.

              -xoffset pixels
                     Specifies  a screen distance to offset the marker horizontally.  Pixels is a
                     valid screen distance, such as 2 or 1.2i.  The default is 0.

              -yoffset pixels
                     Specifies a screen distance to offset the markers vertically.  Pixels  is  a
                     valid screen distance, such as 2 or 1.2i.  The default is 0.

              Marker  configuration  options may also be set by the option command.  The resource
              class is either BitmapMarker,  ImageMarker, LineMarker, PolygonMarker,  TextMarker,
              or WindowMarker, depending on the type of marker.  The resource name is the name of
              the marker.

                     option add *Graph.TextMarker.Foreground white
                     option add *Graph.BitmapMarker.Foreground white
                     option add *Graph.m1.Background     blue

       pathName marker create type ?option value?...
              Creates a marker of the selected type. Type  may  be  either  text,  line,  bitmap,
              image, polygon, or window.  This command returns the marker identifier, used as the
              markerId argument in the other marker-related commands.  If  the  -name  option  is
              used, this overrides the normal marker identifier.  If the name provided is already
              used for another marker, the new marker will replace the old.

       pathName marker delete ?name?...
              Removes one of more markers.  The graph will automatically be redrawn  without  the
              marker..

       pathName marker exists markerId
              Returns 1 if the marker markerId exists and 0 otherwise.

       pathName marker names ?pattern?
              Returns the names of all the markers that currently exist.  If pattern is supplied,
              only those markers whose names match it will be returned.

       pathName marker type markerId
              Returns the type of the marker given  by  markerId,  such  as  line  or  text.   If
              markerId is not a valid a marker identifier, "" is returned.

   BITMAP MARKERS
       A  bitmap marker displays a bitmap.  The size of the bitmap is controlled by the number of
       coordinates specified.  If two coordinates, they specify  the  position  of  the  top-left
       corner  of  the  bitmap.   The  bitmap  retains  its  normal  width  and  height.  If four
       coordinates, the first and second pairs  of  coordinates  represent  the  corners  of  the
       bitmap.   The  bitmap  will  be stretched or reduced as necessary to fit into the bounding
       rectangle.

       Bitmap markers are created with the marker's create operation in the form: pathName marker
       create  bitmap  ?option  value?...   There  may  be  many  option-value pairs, each sets a
       configuration options for the marker.  These same option-value pairs may be used with  the
       marker's configure operation.

       The following options are specific to bitmap markers:

       -background color
              Same as the -fill option.

       -bitmap bitmap
              Specifies  the  bitmap  to  be  displayed.  If bitmap is "", the marker will not be
              displayed.  The default is "".

       -fill color
              Sets the background color of  the  bitmap.   If  color  is  the  empty  string,  no
              background will be transparent.  The default background color is "".

       -foreground color
              Same as the -outline option.

       -mask mask
              Specifies  a  mask  for  the  bitmap to be displayed. This mask is a bitmap itself,
              denoting the pixels that are transparent.  If mask is "", all pixels of the  bitmap
              will be drawn.  The default is "".

       -outline color
              Sets the foreground color of the bitmap. The default value is black.

       -rotate theta
              Sets  the rotation of the bitmap.  Theta is a real number representing the angle of
              rotation in degrees.  The marker is first rotated and then placed according to  its
              anchor position.  The default rotation is 0.0.

   IMAGE MARKERS
       A  image  marker  displays  an  image.  Image markers are created with the marker's create
       operation in the form: pathName marker create image ?option value?...  There may  be  many
       option-value  pairs,  each  sets  a  configuration  option  for  the  marker.   These same
       option-value pairs may be used with the marker's configure operation.

       The following options are specific to image markers:

       -anchor anchor
              Anchor tells how to position the image relative to the positioning  point  for  the
              image.  For  example,  if anchor is center then the image is centered on the point;
              if anchor is n then the image will be drawn such that the top center point  of  the
              rectangular  region  occupied  by the image will be at the positioning point.  This
              option defaults to center.

       -image image
              Specifies the image to be drawn.  If image is "", the marker  will  not  be  drawn.
              The default is "".

   LINE MARKERS
       A line marker displays one or more connected line segments.  Line markers are created with
       marker's create operation in the form:  pathName  marker  create  line  ?option  value?...
       There  may  be  many  option-value pairs, each sets a configuration option for the marker.
       These same option-value pairs may be used with the marker's configure operation.

       The following options are specific to line markers:

       -dashes dashList
              Sets the dash style of the line. DashList is a  list  of  up  to  11  numbers  that
              alternately  represent the lengths of the dashes and gaps on the line.  Each number
              must be between 1 and 255.  If dashList is "", the marker line will be solid.

       -fill color
              Sets the background color of the line.  This color is used with striped lines  (see
              the  -fdashes  option).  If color is the empty string, no background color is drawn
              (the line will be dashed, not striped).  The default background color is "".

       -linewidth pixels
              Sets the width of the lines.  The default width is 0.

       -outline color
              Sets the foreground color of the line. The default value is black.

       -stipple bitmap
              Specifies a stipple pattern used to draw  the  line,  rather  than  a  solid  line.
              Bitmap specifies a bitmap to use as the stipple pattern.  If bitmap is "", then the
              line is drawn in a solid fashion. The default is "".

   POLYGON MARKERS
       A polygon marker displays a  closed  region  described  as  two  or  more  connected  line
       segments.   It  is  assumed  the first and last points are connected.  Polygon markers are
       created using the marker create operation in the  form:  pathName  marker  create  polygon
       ?option  value?...  There may be many option-value pairs, each sets a configuration option
       for the marker.  These same option-value pairs may  be  used  with  the  marker  configure
       command  to  change  the  marker's configuration.  The following options are supported for
       polygon markers:

       -dashes dashList
              Sets the dash style of the outline of the polygon. DashList is a list of up  to  11
              numbers  that  alternately  represent  the  lengths  of  the dashes and gaps on the
              outline.  Each number must be between 1 and 255. If dashList  is  "",  the  outline
              will be a solid line.

       -fill color
              Sets  the  fill  color  of  the  polygon.  If color is "", then the interior of the
              polygon is transparent.  The default is white.

       -linewidth pixels
              Sets the width of the outline of the polygon. If pixels  is  zero,  no  outline  is
              drawn. The default is 0.

       -outline color
              Sets  the color of the outline of the polygon.  If the polygon is stippled (see the
              -stipple option), then this represents the foreground color of  the  stipple.   The
              default is black.

       -stipple bitmap
              Specifies  that  the  polygon should be drawn with a stippled pattern rather than a
              solid color. Bitmap specifies a bitmap to use as the stipple pattern.  If bitmap is
              "",  then  the  polygon  is filled with a solid color (if the -fill option is set).
              The default is "".

   TEXT MARKERS
       A text marker displays a string of characters on one or  more  lines  of  text.   Embedded
       newlines  cause  line  breaks.   They  may be used to annotate regions of the graph.  Text
       markers are created with the create operation in the form:  pathName  marker  create  text
       ?option  value?...  There may be many option-value pairs, each sets a configuration option
       for the text marker.  These  same  option-value  pairs  may  be  used  with  the  marker's
       configure operation.

       The following options are specific to text markers:

       -anchor anchor
              Anchor  tells  how  to  position the text relative to the positioning point for the
              text. For example, if anchor is center then the text is centered on the  point;  if
              anchor  is  n  then  the  text  will be drawn such that the top center point of the
              rectangular region occupied by the text will be at  the  positioning  point.   This
              default is center.

       -background color
              Same as the -fill option.

       -font fontName
              Specifies the font of the text.  The default is *-Helvetica-Bold-R-Normal-*-120-*.

       -fill color
              Sets the background color of the text.  If color is the empty string, no background
              will be transparent.  The default background color is "".

       -foreground color
              Same as the -outline option.

       -justify justify
              Specifies how the text should be justified.  This  matters  only  when  the  marker
              contains  more  than one line of text. Justify must be left, right, or center.  The
              default is center.

       -outline color
              Sets the color of the text. The default value is black.

       -padx pad
              Sets the padding to the left and right exteriors of the text.  Pad can be a list of
              one or two screen distances.  If pad has two elements, the left side of the text is
              padded by the first distance and the right side by the second.  If pad has just one
              distance, both the left and right sides are padded evenly.  The default is 4.

       -pady pad
              Sets  the padding above and below the text.  Pad can be a list of one or two screen
              distances.  If pad has two elements, the area above the text is padded by the first
              distance  and  the area below by the second.  If pad is just one distance, both the
              top and bottom areas are padded evenly.  The default is 4.

       -rotate theta
              Specifies the number of degrees to  rotate  the  text.   Theta  is  a  real  number
              representing  the  angle of rotation.  The marker is first rotated along its center
              and is then drawn according to its anchor position. The default is 0.0.

       -text text
              Specifies the text of the marker.  The exact way  the  text  is  displayed  may  be
              affected by other options such as -anchor or -rotate.

   WINDOW MARKERS
       A  window  marker  displays a widget at a given position.  Window markers are created with
       the marker's create operation in the form: pathName marker create window ?option value?...
       There  may  be  many  option-value pairs, each sets a configuration option for the marker.
       These same option-value pairs may be used with the marker's configure command.

       The following options are specific to window markers:

       -anchor anchor
              Anchor tells how to position the widget relative to the positioning point  for  the
              widget.  For example, if anchor is center then the widget is centered on the point;
              if anchor is n then the widget will be displayed such that the top center point  of
              the  rectangular  region  occupied  by the widget will be at the positioning point.
              This option defaults to center.

       -height pixels
              Specifies the height to assign to  the  marker's  window.   If  this  option  isn't
              specified,  or  if  it is specified as "", then the window is given whatever height
              the widget requests internally.

       -width pixels
              Specifies the width to assign  to  the  marker's  window.   If  this  option  isn't
              specified, or if it is specified as "", then the window is given whatever width the
              widget requests internally.

       -window pathName
              Specifies the widget to be managed by the graph.  PathName must be a child  of  the
              graph widget.

GRAPH COMPONENT BINDINGS

       Specific  graph  components,  such  as  elements,  markers  and legend entries, can have a
       command trigger when event occurs in them, much like canvas items in Tk's  canvas  widget.
       Not  all  event  sequences  are  valid.  The only binding events that may be specified are
       those related to the mouse and keyboard (such as Enter, Leave,  ButtonPress,  Motion,  and
       KeyPress).

       Only  one  element or marker can be picked during an event.  This means, that if the mouse
       is directly over both an element and a marker, only the uppermost component  is  selected.
       This  isn't  true  for  legend  entries.   Both  a legend entry and an element (or marker)
       binding commands will be invoked if both items are picked.

       It is possible for multiple bindings to match a particular event.  This could  occur,  for
       example, if one binding is associated with the element name and another is associated with
       one of the element's tags (see the -bindtags  option).   When  this  occurs,  all  of  the
       matching  bindings  are  invoked.   A  binding associated with the element name is invoked
       first, followed by one binding for each of the element's bindtags.  If there are  multiple
       matching  bindings  for  a  single tag, then only the most specific binding is invoked.  A
       continue command in  a  binding  script  terminates  that  script,  and  a  break  command
       terminates that script and skips any remaining scripts for the event, just as for the bind
       command.

       The -bindtags option for these  components  controls  addition  tag  names  which  can  be
       matched.   Implicitly elements and markers always have tags matching their names.  Setting
       the value of the -bindtags option doesn't change this.

C LANGUAGE API

       You can manipulate data elements from the C language.  There may be situations where it is
       too  expensive to translate the data values from ASCII strings.  Or you might want to read
       data in a special file format.

       Data can manipulated from the C language using BLT vectors.   You  specify  the  X-Y  data
       coordinates  of an element as vectors and manipulate the vector from C.  The graph will be
       redrawn automatically after the vectors are updated.

       From Tcl, create the vectors and configure the element to use them.

              vector X Y
              .g element configure line1 -xdata X -ydata Y

       To set data  points  from  C,  you  pass  the  values  as  arrays  of  doubles  using  the
       Blt_ResetVector  call.   The  vector is reset with the new data and at the next idle point
       (when Tk re-enters its event loop), the graph will be redrawn automatically.

              #include <tcl.h>
              #include <blt.h>

              register int i;
              Blt_Vector *xVec, *yVec;
              double x[50], y[50];

              /* Get the BLT vectors "X" and "Y" (created above from Tcl) */
              if ((Blt_GetVector(interp, "X", &xVec) != TCL_OK) ||
                  (Blt_GetVector(interp, "Y", &yVec) != TCL_OK)) {
                  return TCL_ERROR;
              }

              for (i = 0; i < 50; i++) {
                  x[i] = i * 0.02;
                  y[i] = sin(x[i]);
              }

              /* Put the data into BLT vectors */
              if ((Blt_ResetVector(xVec, x, 50, 50, TCL_VOLATILE) != TCL_OK) ||
                  (Blt_ResetVector(yVec, y, 50, 50, TCL_VOLATILE) != TCL_OK)) {
                 return TCL_ERROR;
              }

       See the vector manual page for more details.

SPEED TIPS

       There may be cases where the graph needs to be drawn and updated as quickly  as  possible.
       If drawing speed becomes a big problem, here are a few tips to speed up displays.

       · Try to minimize the number of data points.  The more data points the looked at, the more
         work the graph must do.

       · If your data is generated as floating point values, the time  required  to  convert  the
         data values to and from ASCII strings can be significant, especially when there any many
         data points.  You can avoid the redundant string-to-decimal conversions using the C  API
         to BLT vectors.

       · Data  elements  without  symbols  are  drawn  faster  than  with  symbols.  Set the data
         element's -symbol option to none.  If you need to draw symbols,  try  using  the  simple
         symbols such as splus and scross.

       · Don't stipple or dash the element.  Solid lines are much faster.

       · If  you  update  data  elements frequently, try turning off the widget's -bufferelements
         option.  When the graph is first displayed, it draws  data  elements  into  an  internal
         pixmap.   The  pixmap acts as a cache, so that when the graph needs to be redrawn again,
         and the data elements or coordinate axes haven't changed, the pixmap is simply copied to
         the  screen.   This  is especially useful when you are using markers to highlight points
         and regions on the graph.  But if the graph is updated frequently, changing  either  the
         element data or coordinate axes, the buffering becomes redundant.

LIMITATIONS

       Auto-scale  routines  do  not  use requested min/max limits as boundaries when the axis is
       logarithmically scaled.

       The PostScript output generated for polygons with more than 1500  points  may  exceed  the
       limits  of  some printers (See PostScript Language Reference Manual, page 568).  The work-
       around is to break the polygon into separate pieces.

KEYWORDS

       graph, widget