2 FCN_DRAW
  Syntax:   FCN_DRAW k xlo xhi ylo yhi
  Defaults: xlo = ALIM,   xhi = BLIM,  ylo = AMIN-20*UP, yhi=AMIN+20*UP.
            (If x has no limits, defaults are x +/- parabolic error)

  Draws FCN as a function of 1 parameter. This command is superceded by
  `FCN_PLOT' and `PROB_PLOT' if you have a graphics device. You can
  give either the parameter number or its name.

  Scans `xlo' to `xhi' in 50 steps  and bins the FCN value from `ylo' to
  `yhi' in 30 steps (so as to fit on 1 page).

  NO check is done on exceeding limits on variable `x' (if any),
  so be careful!

