Provided by: libncarg-dev_6.1.2-7_amd64 bug

NAME

       HISTGR - Plots a histogram with various options including specification of class values,
       spacing between histogram bars, shading of bars, windowing (i.e. scaling), specification
       of color, labels, titles, etc.  Data values are partitioned into classes; histogram bars
       represent either number of occurrences within each class, or a Y-value associated with
       that class (user choice).  Options are set by calls to subroutines HSTOPL, HSTOPR, HSTOPC,
       and HSTOPI before the call to HISTGR.

UTILITY

       This routine is part of the Histogram utility in NCAR Graphics. To see the overview man
       page for this utility, type "man histogram".

SYNOPSIS

       CALL HISTGR (DAT1,NDIM,NPTS,IFLAG,CLASS,NCLASS,WRK,NWRK)

C-BINDING SYNOPSIS

       #include <ncarg/ncargC.h>

       void c_histgr (float *dat1, int ndim, int npts,
       int iflag, float *class, int nclass, float *wrk, int nwrk)

DESCRIPTION

       DAT1        Two dimensional real array containing data of one of two types, either values
                   to be collected into class intervals before plotting, or values which have
                   already been assigned to class intervals and only need to be displayed. See
                   argument IFLAG for a more complete description of HISTGR input data options.
                   DAT1 is dimensioned: DAT1(NDIM,2).

       NDIM        The size of the first dimension of DAT1 as set in the dimension statement of
                   the calling program.

       NPTS        Number of values actually stored into DAT1 on this call. NPTS must always be
                   less than or equal to NDIM.

       IFLAG       An integer flag which selects one of four options provided by the HISTGR
                   utility. The options are:

                   0    A single array of length NPTS is loaded
                        into the DAT1 array. HISTGR computes NCLASS
                        equally sized class intervals that vary
                        from the minimum value in DAT1 to the
                        maximum value in steps of (MAX-MIN)/NCLASS.

                        All values of DAT1 that fall in each
                        class interval are separately accumulated
                        for that interval. The final tabulations
                        are plotted as a histogram of NCLASS bars.
                        The bar height can be labeled with the
                        number of points that fall within this
                        particular class interval (bin size), or
                        it can be given as a percentage of the
                        number of values input, NPTS.

                        Note that under this option the user
                        has no control over the range of the
                        class intervals.  They are internally
                        determined from the range of the data.

                   1    This option is similar to the IFLAG = 0
                        option except that the user can select
                        the range of the class intervals into
                        which the data are collected. For example,
                        say the user wants to collect the number
                        of occurrences of the DAT1 values that
                        fall within 5 equally spaced intervals
                        in the value range from 0. to 10. The
                        user would then input NCLASS+1 class
                        interval end points into array CLASS,
                        namely 0., 2., 4., 6., 8., and 10.
                        These values need not be entered in
                        monotonically increasing order and
                        need not be equally spaced.

                   2    This option allows the user to enter
                        and display data which has already
                        been accumulated into class intervals,
                        i.e., already available histograms.
                        The data input to DAT1 thus have
                        percentage of total, or number of
                        occurrences values. In this case the
                        number of points in DAT1, NPTS, is
                        equal to the number of class intervals
                        (histogram bars), NCLASS. The NCLASS
                        class interval midpoints are loaded
                        into array CLASS. They do not have
                        to be of equal width.

                   3    This option is the same as option
                        IFLAG = 2 except that two histograms
                        can be displayed for comparison
                        purposes. The first histogram is
                        loaded into DAT1(NPTS,1). The second
                        histogram is loaded into DAT1(NPTS,2).
                        The first histogram can partially
                        shade or obscure the second histogram
                        by the appropriate selection of the
                        SPAC and OVERLP options.  Note that
                        NPTS = NCLASS when IFLAG = 2 or 3.

       CLASS       Real array containing class values, dimensioned (NCLASS+1). This array has the
                   following IFLAG dependencies:

                   IFLAG = 0 CLASS is not used.

                   IFLAG = 1 NCLASS+1 class interval end points
                           are loaded into array CLASS in a
                           monotonically increasing order.  The
                           intervals need not be of equal width.

                   IFLAG = 2 NCLASS midpoint intervals are loaded
                           into array CLASS. They must be in
                           monotonically increasing order, but
                           need not be of equal widths. The
                           histogram bars will however be
                           displayed with equal widths.

                   IFLAG = 3 Same as for IFLAG = 2.

       NCLASS      Number of class intervals (histogram bars) specified.  NCLASS must be .GE. 1.

       WRK         Real scratch array, dimensioned by NWRK in the dimension statement of the
                   calling program.

       NWRK        The dimension size of array WRK determined from: NDIM + 3 * (NCLASS + 1)

C-BINDING DESCRIPTION

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

       dat1        Two dimensional real array dimensioned: dat1(2,ndim).

       ndim        The size of the second dimension of dat1 as set in the dimension statement of
                   the calling program.

USAGE

       Many parameters which affect the output histogram can be set before this routine is
       called.  See the histogram_params man page for a short functional description of all
       available parameters.  For more detail on a specific option, see the man pages of the
       parameter setting routines (HSTOPC, HSTOPI, HSTOPL, or HSTOPR) used to set the parameters
       defining that option.

EXAMPLES

       Use the command "ncargex thstgr" to generate a three frame example of various types of
       histograms.  "ncargex thstmv" will show three examples of histograms with missing values
       in the input data.

ACCESS

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

MESSAGES

       See the histogram man page for a description of all Histogram error messages and/or
       informational messages.

SEE ALSO

       Online: histogram, histogram_params, hstopc, hstopi, hstopl, hstopr, ncarg_cbind

       Hardcopy: NCAR Graphics Fundamentals, UNIX Version

COPYRIGHT

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

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