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

begin 
  x = fspan(-100,100,500)                     ; 500 values from -100 to 100.
  y = asciiread("xy2.txt",(/500,4/),"float")
  y!0 = "npts"
  y!1 = "ncurves"
  y2  = y(ncurves|:,npts|:)           ; Reorder dimensions to 4 x 500.

  wks = gsn_open_wks ("x11","xy2_ex03")

  res  = True                           ; Plot options desired.

  res@gsnMaximize       = True          ; Maximize plot in frame.

  res@xyMonoDashPattern = True             ; Use one dash pattern (solid)
  res@xyLineThicknesses = (/1.,2.,3.,4./)  ; Line thicknesses
  res@xyLineColors      = (/"NavyBlue","HotPink","OrangeRed","ForestGreen"/)

  plot = gsn_csm_xy (wks,x,y2,res)     ; Call the gsn_csm function
                                       ; for drawing the curves.
end