Name:         GRGRAY

Purpose:      gray-scale map of a 2D data array

Category:     GRAPHICS

File:         pgplot.src

Author:       T.J. Pearson

Use:          see description below.

Description:

            SUBROUTINE GRGRAY (A, IDIM, JDIM, I1, I2, J1, J2,
           1                   FG, BG, PA, MININD, MAXIND, MODE)
            INTEGER IDIM, JDIM, I1, I2, J1, J2, MININD, MAXIND, MODE
            REAL    A(IDIM,JDIM)
            REAL    FG, BG
            REAL    PA(6)
      
       This is a device-dependent support routine for PGGRAY.
      
       Draw gray-scale map of an array in current window. Array
       values between FG and BG are shaded in gray levels determined
       by linear interpolation. FG may be either less than or greater
       than BG.  Array values outside the range FG to BG are
       shaded black or white as appropriate.
      
       GRGRAY uses GRIMG0 on devices with enough color indices available.
       Note that it changes the color table to gray-scale.
       Otherwise in does a random dither with GRIMG3.
      
       Arguments:
        A      (input)  : the array to be plotted.
        IDIM   (input)  : the first dimension of array A.
        JDIM   (input)  : the second dimension of array A.
        I1, I2 (input)  : the inclusive range of the first index
                          (I) to be plotted.
        J1, J2 (input)  : the inclusive range of the second
                          index (J) to be plotted.
        FG     (input)  : the array value which is to appear in
                          foreground color.
        BG     (input)  : the array value which is to appear in
                          background color.
        PA     (input)  : transformation matrix between array grid and
                          device coordinates (see GRCONT).
        MODE   (input)  : transfer function.

Updates:      Oct 16, 1998: JPT automatically extracted from source.