begin

;
; Create some data for the contour plot.
;
  M=25
  N=25
 
  T = new((/N,M/),float)
 
  jspn = ispan(-M/2,M/2,1)^2
  ispn = ispan(-N/2,N/2,1)^2
  do i = 0, dimsizes(ispn)-1
      T(i,:) = ispn(i) + jspn
  end do
  T = 100.0 - sqrt(8^2 * T)

;
; Create an X workstation.
;
  wid = create "wks" xWorkstationClass defaultapp end create

;
; Create a data object.
;
  dataid = create "data" scalarFieldClass defaultapp
    "sfDataArray" : T
    "sfXCStartV"  : -90.0   ; minimum longitude value for overlay
    "sfXCEndV"    :  90.0   ; maximum longitude value for overlay
    "sfYCStartV"  : -45.0   ; minimum latitude value for overlay
    "sfYCEndV"    :  45.0   ; maximum latitude value for overlay
  end create

;
; Create a ContourPlot object.
;
  cnid = create "ContourPlot" contourPlotClass wid
    "cnScalarFieldData" : dataid
  end create

;
; Create the default MapPlot object.
;
  mpid = create "MapPlot" mapPlotClass wid end create
  
  overlay(mpid,cnid) ; Overlay contour plot on map plot.
  draw(mpid)         ; Draw map plot (contour plot will be drawn too).
  frame(wid)         ; Advance frame.
end