load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"

begin 
  y = asciiread("xy2.txt",(/500,4/),"float")

  wks = gsn_open_wks ("ps","xy2_ex")

  res  = False                      ; No plot options desired.

  plot = gsn_csm_y (wks,y(:,0),res) ; Call the gsn_csm function
                                    ; for drawing one curve.
end