Gaussian Fit on TH2F

Hello,
I am using root version 5.26. My problem is not exactly root problem but a generic fitting problem on 2D histograms. I am sorry if it is inappropriate to ask about here. I am trying to make a Gaussian fit on many different 2D histograms with two prominent peaks on each but moving around from histogram to histogram. Later, I will also try other histograms with multiple peaks. I am using a fit function like:
double g2(double *x, double *par)
{

    double r1 = double((x[0]-par[1])/par[2]);     double r2 = double((x[1]-par[3])/par[4]);     return par[0]*TMath::Exp(-0.5*(r1*r1+r2*r2)); }
Also tried combination fit like:
double fun2(double *x, double *par)
{

    double *p1 = &par[0];
    double *p2 = &par[5];
    double result = g2(x,p1) + g2(x,p2);     return result;
}
But in both cases, the fit result is hugely dependent on the the initial parameters and often fails for many of the histograms since the peaks are moving around. Only way I could think is to find peak locations in each histogram and supply initial parameters based on those. I would like to ask your opinions if this is worth trying or are there better ways. Thanks, - Nevzat Guler Received on Mon Nov 01 2010 - 09:01:59 CET