%N pghi2d %F $MIR/src/pghi2d.f
%D Cross-sections through a 2D data array
%B
      SUBROUTINE PGHI2D (DATA, NXV, NYV, IX1, IX2, IY1, IY2, X, IOFF,
     1                   BIAS, CENTER, YLIMS)
      INTEGER NXV, NYV, IX1, IX2, IY1, IY2
      REAL    DATA(NXV,NYV)
      REAL    X(IX2-IX1+1), YLIMS(IX2-IX1+1)
      INTEGER IOFF
      REAL    BIAS
      LOGICAL CENTER

 Plot a series of cross-sections through a 2D data array.
 Each cross-section is plotted as a hidden line histogram.  The plot
 can be slanted to give a pseudo-3D effect - if this is done, the
 call to PGENV may have to be changed to allow for the increased X
 range that will be needed.

 Arguments:
  DATA   (input)  : the data array to be plotted.
  NXV    (input)  : the first dimension of DATA.
  NYV    (input)  : the second dimension of DATA.
  IX1    (input)
  IX2    (input)
  IY1    (input)
  IY2    (input)  : PGHI2D plots a subset of the input array DATA.
                    This subset is delimited in the first (x)
                    dimension by IX1 and IX2 and the 2nd (y) by IY1
                    and IY2, inclusively. Note: IY2 < IY1 is
                    permitted, resulting in a plot with the
                    cross-sections plotted in reverse Y order.
                    However, IX2 must be => IX1.
  X      (input)  : the abscissae of the bins to be plotted. That is,
                    X(1) should be the X value for DATA(IX1,IY1), and
                    X should have (IX2-IX1+1) elements.  The program
                    has to assume that the X value for DATA(x,y) is
                    the same for all y.
  IOFF   (input)  : an offset in array elements applied to successive
                    cross-sections to produce a slanted effect.  A
                    plot with IOFF > 0 slants to the right, one with
                    IOFF < 0 slants left.
  BIAS   (input)  : a bias value applied to each successive cross-
                    section in order to raise it above the previous
                    cross-section.  This is in the same units as the
                    data.
  CENTER (input)  : if .true., the X values denote the center of the
                    bins; if .false. the X values denote the lower
                    edges (in X) of the bins.
  YLIMS  (input)  : workspace.  Should be an array of at least
                    (IX2-IX1+1) elements.
