TFractionFitter fraction values do not add to unity

Hello Rooters!

I have 1D histogram of experimental data. I have to fit with 5 MC 1D histograms. I fitted it but when I added all fractions of MC histogram, it did not give 1.0 but close to unity. Is there any way I can get unity it I add all fractions of MC histogram. I saw in TFractionFitter code, it is normalizing the factor. But, I am not getting it. I am new to TFractionFitter, it might be very stupid question. Thanks in advance.


The sum of the fitted fractions of TFractionFitter should be equal to 1. Maybe you are having a numerical error in the sum ?
If not, something else might not be correct. I would need in that case your code and input histograms


TFraction.C (5.1 KB)
histograms.root (6.4 KB)

I want to minimize the fit by looping the fraction of hist_712 and finding the corresponding fractions of other MC histograms with minimum chisquare in each point in loop. I want how other fractions of simulated histograms change with change in fraction of hist_712. I added the all fraction values before and after the fit. I chose initial fractions first getting minimization without loop and adjust to make sum before fit equal to unity ( you can also check). But after the fit in loop, the sum of all fractions is not exactly unity. Thank you in advance.


Thanks for posting the code. Your problem is more elaborate, I’ll look at it and try to understand it


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