anchor.diff:        fill_width = 2
         cont_color = 0
         cont_width = 0
  -      call plshades(z, defined, -1._plflt, 1._plflt, -1._plflt, &
  -        1._plflt, &
  -        shedge, fill_width, &
  -        cont_color, cont_width, xg1, yg1 )
  +      call plshades(z(:NX,:NY), defined, -1._plflt, 1._plflt, -1._plflt, &
  +        1._plflt, &
  +        shedge, fill_width, &
  +        cont_color, cont_width, xg1(:NX), yg1(:NY))
   
         call plcol0(1)
         call plbox('bcnst', 0.0_plflt, 0, 'bcnstv', 0.0_plflt, 0)
  
positive.code:       fill_width = 2
        cont_color = 0
        cont_width = 0
        call plshades(z, defined, -1._plflt, 1._plflt, -1._plflt, &
          1._plflt, &
          shedge, fill_width, &
          cont_color, cont_width )
  
negative.code:       fill_width = 2
        cont_color = 0
        cont_width = 0
        call plshades(z(:NX,:NY), defined, -1._plflt, 1._plflt, -1._plflt, &
          1._plflt, &
          shedge, fill_width, &
          cont_color, cont_width, xg2(:NX,:NY), yg2(:NX,:NY) )
  
  !      Now we can draw the perimeter.  (If do before, shade stuff may overlap.)
        do i = 1, PERIMETERPTS
  