2 FCN_PLOT
  Syntax: FCN_PLOT name|number xlo xhi ylo yhi
   where: name    is the name of the variable you want to plot
          number  is the parameter number
          xlo     is the minimum value
          xhi     is the maximum value
          ylo     is the minimum value of the chi**2 or likelihood
          yhi     is the maximum value of the chi**2 or likelihood

  Plots the chi**2 or likelihood as a function of one of the fit
  parameters. NO check is done on exceeding limits on variable `x' (if
  any), so be careful!  You can give either the parameter number or
  its name. See HELP MINUIT PROB_PLOT and HELP MINUIT CHI_PLOT for
  other ways to plot the fit probability as a function of the value of
  a variable. See HELP MINUIT MNCONTOUR for contour plots.

