[ROOT] Fitting over multiple ranges

From: Alberto Pulvirenti (alberto.pulvirenti@ct.infn.it)
Date: Thu Jul 08 2004 - 19:29:48 MEST

Dear ROOTers,

I encountered a problem which I wish to solve.
I have a plot which looks like the sum of two gaussians with similar 
mean and quite different constant/sigma values.
I would like to fit such a histogram with the sum of two gaussians.

Given that one of the two is smaller and wider, I wished to try to fuit 
a gaussian in the middle part of the histo (and I know how to do this)
And the other should be fitted at the same time, in the two periperical 

Say, if we divide the histo into three regions: (-A, -0.1), (-0.1, 0.1) 
and (0.1, A), how can I perform a fit with the same function, and 
simultaneously in the two ranges (-A, -0.1) + (0.1, A) ?
(I tried with two separate gaussian fit on the two intervals, but the 
result is not satisfactory).


Alberto Pulvirenti, Ph. D.
University of Catania / INFN Catania
Address: Via S. Sofia, 64 I-95123 Catania
   Phone: +39-095-378-5286

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