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P.d.f value is not a number Roofit

Roofit and RooStats
#1

Hello root family,

I had a problem with some weights in the TMVA Fatal error TMVA signalweight, for that reason I was checking for the beginning and I notice that in the Roofit in the pdf of exponencial (for my background signal) I have the next warning

Captura de pantalla de 2020-09-13 11-56-58
Captura de pantalla de 2020-09-13 11-56-581366×768 273 KB

but they continue and compile right, and show me the values for my parameters. After that I’m able to calculate and save the Weights.

My question is if this Warning “p.d.f value is Not-a-Number (-nan), forcing value to zero @ pdf=exponencial=inf/-nan, n=Nb=1.13659e+06” is causing me the error in my TMVA Fatal error TMVA signalweight

And I want to know how to fix this warning, beacuse in the other parameters Root does not show me that warning
This is my code:
pruebavalor.C (5.2 KB)

Thanks for your time

#2

FYI, I’ve invited our RooFit expert @StephanH to have a look at this!

#3

Hi @Manuel_Torres,

what I see from the error message is that the exponential PDF diverges to infinity, and when RooFit tries to integrate over an infinite function, the result is not a number.
In the second line, you have the parameter values that cause the problems. I imagine your model has to compute 2875^202, which is a very large number.

If this only happens during the fit (because the minimiser takes a step in the wrong direction), but then the fit continues in the right direction, it’s not a problem. If the fit stops in this point, the fit model is unstable.

#4

Thank you, the fit continues in the right direction.