Re: Fit problem

You must protect your function shift_Poiss against division by 0.

Rene Brun

Vassili Maroussov wrote:
> Dear ROOTers,
>
> for some reason fitting macros which were perfectly working with
> ROOT4.03 do not work with ROOT5.11 When I execute a short sample macro
> test_fit_0.C I get the 2 long series of error messages:
>
> ----------------------------------------------------------------------
> [pcmspur5] ~/Preselection > root -l
>
> Welcome to the ROOT tutorials
>
>
> Type ".x demos.C" to get a toolbar from which to execute the demos
>
> Type ".x demoshelp.C" to see the help window
>
> ==> Many tutorials use the file hsimple.root produced by hsimple.C
> ==> It is recommended to execute hsimple.C before any other script
>
> root [0] .x test_fit_0.C
> Error: operator '/' divided by zero test_fit_0.C:3:
> Error: operator '/' divided by zero test_fit_0.C:3:
> Error: operator '/' divided by zero test_fit_0.C:3:
>
> ****
>
> Error: G__CallFunc::SetArgArray() must be initialized with
> 'G__CallFunc::SetFunc(G__ClassInfo* cls,char* fname,char* args,long*
> poffset)' first
> Error: G__CallFunc::SetArgArray() must be initialized with
> 'G__CallFunc::SetFunc(G__ClassInfo* cls,char* fname,char* args,long*
> poffset)' first
> Error: G__CallFunc::SetArgArray() must be initialized with
> 'G__CallFunc::SetFunc(G__ClassInfo* cls,char* fname,char* args,long*
> poffset)' first
>
> ****
> .q
>
> This is the end of ROOT -- Goodbye
>
> [pcmspur5] ~/Preselection >
> ----------------------------------------------------------------------
>
> What is wrong with the macro?
>
> Regards,
>
> Vassili.
>
>
> ------------------------------------------------------------------------
>
> Double_t shift_Poiss(Double_t *x, Double_t *par)
> {
> Double_t var = x[0]/par[2] - par[1];
> return par[0] * TMath::Exp(var * TMath::Log(par[3])-par[3])/TMath::Gamma(var+1.0);
> }
>
> void test_fit_0()
> {
> TFile *f = new TFile("Test_Fit.root", "READ");
> TCanvas *c1 = new TCanvas("c1","Multiplicity distribution");
> TH1F *h1f_ntrk_S = (TH1F*)f->Get("h1f_ntrk_S");
>
> // Creates a ROOT function TF1 to fit
> TF1 *fit1 = new TF1("fit1",shift_Poiss,6,60,4);
>
> // Sets initial values, limits and parameter names
> fit1->SetParameters(300000,0,1.5,5);
>
> fit1->SetParLimits(0,1,100000000);
> fit1->SetParLimits(1,0,100);
> fit1->SetParLimits(2,0.1,100);
> fit1->SetParLimits(3,1,100);
>
> fit1->SetParNames("Ampl","Shift","Scale","Mean");
>
> // Fit histogram in range defined by function
> h1f_ntrk_S->Fit("fit1","r");
> }
>
Received on Tue Sep 05 2006 - 23:20:58 MEST