mpsteppar

       plot 1D or 2D chi^2 contours for chi^2 fitting error determination

       fitting

       steppar,x,y,w,a plus lot's of keywords

       x,y,w: (x,y) values and weight of data, identical to
              curvefit
       a: best fit parameters of the fit function

     * required:
         par1ind: index of 1st parameter to be stepped
         par1min,par1max: min. and max. value of 1st parameter
         nstep1: number of steps for par1
     * optional:
         par1log: if set, use logarithmic steps
         par2ind,par2min,par2max,nstep2,par2log: same as
            the ..1.. pars for the 2nd parameter to be stepped.
         bestnorm: chi^2 at minimum (result from bestnorm keyword
                of mpfitfun)
         plot: if set, a plot of chi^2 vs. the parameter(s) is
            shown, with contours indicating the 1sigma, 90%, and 99%
            confidence regions (the latter option requires the
            bestnorm value as well!).
         dev: plot axes as deviation from best fit value
         xtitle: lable for the x-axis (default, if there is a parname
            tag available, name of the fit parameter)
         ytitle: same as xtitle, only for (guess what) the y-axis; in
            the case of 2d contours only
         chatty: report progress
       * All keyword-parameters given to the previous call to
         mpfitfun.

       par1val: values of 1st parameter
       par2val: values of 2nd parameter
       chi2val: array containing the chi^2 values

       none

       if /plot is set, a (contour) plot is drawn in the current window

       stepping regions need to contain the best fit value.

     based on steppar.pro, written 1999.03.03 by Joern Wilms
     CVS Version 1.0, 2001.12.06, Joern Wilms
         (mainly written while at SSO in October 2001)
 DO NOT MODIFY ANYTHING BELOW THIS LINE: RCS LOG
 $Log: mpsteppar.pro,v $
 Revision 1.6  2003/06/17 14:18:36  goehler
 added verbose option which reports progress
 Revision 1.5  2003/02/24 14:44:52  goehler
 support extra function arguments in the 1-dim special case
 where no free parameters are are used. The parameters are
 passed via _extra keyword.
 Revision 1.4  2002/08/15 13:16:34  goehler
 exported parameter 2 to support external plot routines
 Revision 1.3  2002/06/03 21:15:16  wilms
 changed header (removed old keywords from jwsteppar).
 added code such that parinfo is not a required keyword anymore
 Revision 1.2  2002/05/10 09:59:24  wilms
 * added xtitle and ytitle keywords
 * took care of special case that there are no free parameters. In this
   case, chi^2 is computed directly.

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