NAME

     define_histogram - Enables a user to specify a histogram  in
     terms of a variable 'x'.

SYNOPSIS

     #include "histogram.h"

     float **define_histogram(int bands, int mode, char **eq)

      <bands> - number of bands in the image
      <mode> - prompt the user for input (mode=1),
               or use <eq> (mode=0)
      <eq> - string for mapping equation

PATH

     $CVIPHOME/HISTOGRAM/histogram.c

DESCRIPTION

     define_histogram is used  to  generate  a  histogram  to  be
     passed  to  the  histogram_spec function.  This function can
     either work interactively when mode = 1, or use  the  string
     to  generate  the histogram when mode = 0. When mode = 1, it
     asks the user to enter an equation in terms of 'x' for  each
     band in the image.

     The following functions may be specified:

     sin(arg)
     cos(arg)
     tan(arg)
     asin(arg)
     acos(arg)
     atan(arg)
     sinh(arg)
     cosh(arg)
     tanh(arg)
     exp(arg)
     ln(arg)
     log(arg)
     sqrt(arg)
     floor(arg)
     ceil(arg)
     abs(arg)
     hypot(arg1,arg2)
     deg(arg)
     rad(arg)
     imp(arg)
     impulse(arg)
     step(arg)
     u(arg)
     ramp(arg)
     r(arg)
     random(low val,high val)

RETURN VALUES

     On success, this function returns a pointer of pointer to  a
     float,  with  dimensions  float[int][256],  where int is the
     integer passed to the function.

BUGS

     It could fail if complicated equations are specified.

SEE ALSO

     get_histogram,        get_histogram_Image,        hist_spec,
     histogram_show,        histogram_spec,       make_histogram,
     showMax_histogram

AUTHOR

     Copyright (C) 1992, 1996 SIUE - by Scott E.  Umbaugh,  David
     A. Lyons and Yansheng Wei.