Ubuntu Manpage: CPCNRC - Draws black and white contours with a single call. the behavior of the old

NAME

       CPCNRC - Draws black and white contours with a single call.  the behavior of the old
       routine CONREC; it has the same arguments and produces similar output.

SYNOPSIS

        CALL CPCNRC (ZDAT, KZDT, MZDT, NZDT, FLOW, FHGH, FINC,
       + NSET, NHGH, NDSH)

C-BINDING SYNOPSIS

       #include <ncarg/ncargC.h>

       void c_cpcnrc (float *zdat, int kzdt, int mzdt, int nzdt,
       float flow, float fhgh, float finc, int nset, int nhgh,
       int ndsh)

DESCRIPTION

ZDAT (REAL array, dimensioned KZDT x n, where "n" is greater than or equal to NZDT,
input) is the array containing the data to be contoured.

KZDT (INTEGER, input) is the first dimension of the FORTRAN array ZDAT.

MZDT (INTEGER, input) is the first dimension of the array of data in ZDAT. MZDT
must be less than or equal to KZDT.

NZDT (INTEGER, input) is the second dimension of the array of data in ZDAT. NZDT
must be less than or equal to the declared second dimension of the array ZDAT.

FLOW (REAL, input) is the desired lowest contour level. If FLOW is equal to or
greater than FHGH, Conpack will choose the set of contour levels.

FHGH (REAL, input) is the desired highest contour level. If FHGH is equal to or
less than FLOW, Conpack will choose the set of contour levels.

FINC (REAL, input) says how contour levels are to be chosen. There are two
possibilities:

• If FINC is greater than zero, it specifies the desired contour interval to
be used. In this case, if FLOW is less than FHGH, the intervals used will
be FLOW, FLOW+FINC, FLOW+2*FINC, ... FLOW+n*FINC, where "n" is the largest
integer such that FLOW+n*FINC is less than or equal to FHGH. If FLOW is
greater than or equal to FHGH, the contour levels will be those integer
multiples of FINC which fall between the minimum value in ZDAT and the
maximum value in ZDAT.

• If FINC is less than or equal to zero, Conpack will choose the contour
interval in such a way as to give at least 16 contour levels (if FINC is
zero) or MAX(1,INT(-FINC)) contour levels (if FINC is less than zero)
between the minimum and maximum values in ZDAT. All the contour levels
will be integer multiples of the chosen interval. If FLOW is less than
FHGH, no contour lines will be drawn for chosen contour levels which are
outside the range (FLOW,FHGH).

NSET (INTEGER, input) says how the contour plot is to be mapped onto the plotter
frame. There are three basic possibilities:

• If the value of NSET, modulo three, is zero, the "standard configuration"
will be used. Conpack will be directed to call SET. The portion of the
plotter frame bounded by the lines "X=.05", "X=.95", "Y=.05", and "Y=.95"
(in the "fractional" or "normalized-device-coordinate" system) will be
used. The shape of the plot will be determined by the values of the
internal parameters 'WDL', 'WDR', 'WDB', and 'WDT'; by default, the ratio
of the plot's width to its height will be MZDT/NZDT. If the ratio of the
width to the height is less than 1/4 or greater than 4, the plot will be
made square. CPBACK will be called to draw a perimeter.

• If the value of NSET, modulo three, is equivalent to minus one, the
contour plot will fill the current viewport. Conpack will be directed to
call SET. The portion of the plotter frame used will be that bounded by
the lines "X=xl", "X=xr", "Y=yb", and "Y=yt", where "xl", "xr", "yl", and
"yr" are obtained by means of a

CALL GETSET (xl,xr,yl,yr,...)

The plot will fill this entire area. CPBACK will not be called to draw a
perimeter.

• If the value of NSET, modulo three, is equivalent to plus one, Conpack
will be directed not to call SET. It will be assumed that the user has
done the appropriate call. CPBACK will not be called to draw a perimeter.
Use this option when overlaying CPCNRC output on an existing background
(one drawn by Ezmap, for example).

If the value of NSET is -1, 0, or 1, CPCNRC will, prior to returning control
to the caller, restore the SET call to what it was on entry (which is how
CONREC works). If the value of NSET is less than -1 or greater than 1, CPCNRC
will not so restore the SET call; this may be useful if other objects are to
be drawn on the plot produced by CPCNRC.

NHGH (INTEGER, input) says whether highs and lows or data points are to be labeled.
There are three possibilities:

• If NHGH is zero, each high is marked with an "H" and each low is marked
with an "L"; the value is written as a subscript of the "H" or "L".

• If NHGH is greater than zero, each data point is marked with the value at
that point. No attempt is made to cull overlapping values, so using this
option when there are too many data points may result in a mess. The
values of the Conpack parameters 'HLA' and 'HLS' are retrieved and used to
determine the angle at which the values are written and the size of the
characters used. They may be used to reduce the clutter somewhat.

• If NHGH is less than zero, neither of the above is done.

NDSH (INTEGER, input) may be used to specify a 10-bit dash pattern to be used. (If
ABS(NDSH) is 0, 1, or 1023, all solid lines are used.) If NDSH is greater than
zero, the specified dash pattern is used for all contour lines; if NDSH is
less than zero, the dash pattern is used only for negative-valued contour
lines. Note: the 10-bit pattern is actually made into a 16-bit pattern by
appending a copy of the high-order six bits.

C-BINDING DESCRIPTION

       The C-binding argument descriptions are the same as the FORTRAN argument descriptions with
       the following exceptions:

       zdat        Dimensioned n by kzdt, where n is greater than or equal to nzdt.

       kzdt        The second dimension of the array zdat.

       mzdt        The second dimension of the array of data in zdat.  mzdt must be less than or
                   equal to kzdt.

       nzdt        The first dimension of the array of data in zdat. nzdt must be less than or
                   equal to the declared first dimension of the array zdat.

USAGE

The appearance of the plot produced by CPCNRC may vary, depending on the setting of
internal parameters of Conpack. The following should be noted:

• By default, contour lines will be labeled using the old CONREC scheme of appending the
label for a line to the dash pattern for the line. To use one of the new schemes,
place a

CALL CPSETI ('LLP - LINE LABEL POSITIONING',n)

where n has the value 2 or 3, before the call to CPCNRC. CPCNRC retrieves the value
of 'LLP' and, if the value is a 2 or a 3, modifies the calls that it performs so as to
properly shield labels from having contour lines drawn through them.

• By default, high-quality characters will be used in the informational label, in
high/low labels, in point-value labels, and in contour-line labels written when 'LLP'
is 2 or 3. To use lower-quality characters, place a

CALL PCSETI ('QUALITY',1)

or a

CALL PCSETI ('QUALITY',2)

prior to the call to CPCNRC.

Note that these calls are to subroutines that start with the letters PC, because the
routine you are calling is in the utility Plotchar. (Conpack uses Plotchar to plot
characters.)

• If the output from CPCNRC is to be overlaid on an Ezmap background and longitude is a
linear function of the first subscript of the data array and latitude is a linear
function of the second subscript of the data array, you can

Call Ezmap to draw the background.

Set the parameter 'MAP' to 1.

Set the parameters 'XC1', 'XCM', 'YC1', and 'YCN' to specify the longitude and
latitude ranges. Note: 'XCM' must be numerically larger than 'XC1'. If, for
example, your data run from 175 degrees east of Greenwich at the left edge to
160 degrees west of Greenwich at the right edge (which is -160 degrees east),
then you should set 'XC1' = 175 and 'XCM' = 200 to achieve the proper mapping.

Call CPCNRC to draw the contour plot.

• To smooth the contour lines in the same way that they would have been smoothed by the
"smooth" or "super" versions of CONREC, insert

CALL CPSETR ('T2D - TENSION ON THE 2D SPLINES',t),

where t is the desired tension, to turn on the smoother.

• By default, no scale factor is used. (Because Conpack can write contour line labels in
scientific notation, it was considered less important to use a scale factor.) If you
want to use a scale factor, the value of the internal parameter 'SFS' should be set
prior to calling CPCNRC.

• CPCNRC contains a real workspace array, an integer workspace array, and an area map,
which is used to prevent contour lines from passing through labels when 'LLP' has the
value 2 or 3. The lengths of these arrays are 5000, 2000, and 12000, respectively. If
this proves insufficient, you must obtain a copy of the code for CPCNRC, adjust the
dimensions as required, and compile it in place of the default version.

• Certain internal parameters are used by CPCNRC; user calls to reset them prior to the
call to CPCNRC will therefore have no effect. These parameters are as follows:

'AIA' 'AIB' 'CIS' 'CIU' 'CLC' 'CLD' 'CLL' 'CLS' 'CLV' 'CLU' 'CMN' 'CMX' 'HLT' 'HIT'
'LOT' 'LLC' 'LLT' 'NCL' 'SET' 'VPB' 'VPL' 'VPR' 'VPS' 'VPT'

• Subroutines with names of the form CPCHxx (the change subroutines) will be of more
value when used in conjunction with CPCNRC than when used in conjunction with the more
basic Conpack subroutines. For example, the only way to change the color of the zero
contour line drawn by a call to CPCNRC is to supply your own version of the routine
CPCHCL; there is no way, short of modifying the code of CPCNRC, to use the internal
parameter that controls the color of the zero contour line.

• Like CONREC, CPCNRC does no call to FRAME. To advance the frame, put a CALL FRAME
after the call to CPCNRC.

EXAMPLES

       Use the ncargex command to see the following relevant examples: ccpcnrc, cpex09, tconpa.

ACCESS

       To use CPCNRC or c_cpcnrc, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c,
       preferably in that order.

COPYRIGHT

       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research

       The use of this Software is governed by a License Agreement.