2 CHI_PLOT
  Syntax: CHI_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
          yhi     is the maximum value of the chi**2

  Draws the chi**2 as a function of one of the fit parameters. If you
  are doing a likelihood fit the proper chi**2 is calculated using the
  square root of the value of the function as the error. 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 FCN_PLOT and HELP MINUIT PROB_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.

