PRO writexy, file, x, y

; Write a 1d function into a free-format 2-column file

  openw,lun,file,/get_lun
  xx = 0.d0 & yy = 0.d0

  ndat = n_elements(x)
  FOR i = 0,ndat-1 DO BEGIN
    xx = x(i) & yy = y(i)
    PrintF, format='(2e16.7)', lun, xx,yy
  ENDFOR

  close,lun
  free_lun, lun

END