Fit in ROOT 5.23/02: "Warning in <Fit>: Fit data is empty"

From: Cristian Andrei <andrei.cristi_at_gmail.com>
Date: Fri, 27 Mar 2009 22:26:55 +0200


Hello everyone,

I'm trying to fit a TH1D using a rather complicated function. The TH1D was generated by me, before, using the same function with some fixed parameters values. So I hope to find by fitting the parameters values that I previously set.

I basically do:

//-----------------------------------------------------------------------------------------
// generate the TH1D in another script

 TH1D* hist = (TH1D*)file.Get("hist");

 TVirtualFitter::SetDefaultFitter("Minuit2"); //same thing happens with Fumili, Fumili2 and Minuit

 TF1 *Fit = new TF1("Fit",fit_func,x1,x2,3); //3 parameters

 hist->Fit("Fit","V R ME I");

//-----------------------------------------------------------------------------------------

Info in <Minuit2>: MnHesse: 2nd derivative zero for Parameter  : i = 0
Info in <Minuit2>: MnHesse fails and will return diagonal matrix
Warning in <TH1D::Fit>: Abnormal termination of minimization.
Info in <Minuit2>: MnHesse: 2nd derivative zero for Parameter  : i = 0
Info in <Minuit2>: MnHesse fails and will return diagonal matrix
Info in <Minuit2>: MnHesse: 2nd derivative zero for Parameter  : i = 0
Info in <Minuit2>: MnHesse fails and will return diagonal matrix
TFitterMinuit::MINOS failed due to invalid function minimum

I have find /trunk/math/minuit2/src/MnHesse.cxx Revision 27589, so last night I have installed the latest trunk version.
* Now when I run the same exact script on ROOT 5.23/02 on linux I get:

Warning in <Fit>: Fit data is empty

Thank you very much for any help.

-- 
Cristian ANDREI
Received on Fri Mar 27 2009 - 21:26:59 CET

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