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

begin 
  npts    = 500                      ; number of points
  ncurves = 4                        ; number of curves

  ym = asciiread("xy2.txt",(/npts,ncurves/),"float")
  x  = fspan(-50,50,npts)         ; npts values from -50 to 50
  y  = ym(:,0)                    ; Just grab one set of points.

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

  res  = True                      ; Plot options desired.

  res@trXMinF = min(x)             ; Put limits on X axis.
  res@trXMaxF = max(x)

  plot = gsn_csm_xy (wks,x,y,res)
end