anchor.diff:  C Create a horizontal 2-dimensional grid
   C----
         IMPLICIT NONE
  -      REAL x1,x2,y1,y2,dx,dy
  -      REAL x,y,z
  +      REAL*8 x1,x2,y1,y2,dx,dy
  +      REAL*8 x,y,z
         INTEGER i,j,nx,ny,chk,p
   
   C----
  
positive.code:       SUBROUTINE gcmdln(x1,x2,y1,y2,nx,ny,z,p)
        IMPLICIT none
        CHARACTER*20 tag
        REAL x1,x2,y1,y2,z
        INTEGER narg,i,nx,ny,p
  
        x1 = 0.0
        x2 = 1.0
        y1 = 0.0
        y2 = 1.0
        nx = 0
        ny = 0
        z = 0.0
        p = 0
        
        narg = iargc()
  
negative.code:       write(*,*)
       1 '  -z [Z]     (Default Z=0) define z'
        write(*,*)
       1 '  -nx [NX]   (Default NX=1) define number of x grid points'
        write(*,*)
       1 '  -ny [NY]   (Default NY=1) define number of y grid points'
        write(*,*)
       1 '  -p         (Default off) print output to stdout (will not ',
       2                            'write file grid.out)'
  