TH1::IntegralError question

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Hi,

I have similar problem, I am confused about what changed and how to use IntegralError now.

so I have a combined fit function:

TF1 *total = new TF1(“total”,“expo(0)+expo(2)+expo(4)”,0,5);
total->SetParameters(par);
hpT->Fit(total,“R”);

and it works great, the I want to get integral of the first exponent on some range, and its ERROR,
so I define new function expoGG:

TF1 *expoGG = new TF1(“expoGG”,“expo”,0.0,5);

expoGG->SetParameter(0,total->GetParameter(0));
expoGG->SetParameter(1,total->GetParameter(1));
expoGG->SetParError(0,total->GetParError(0));
expoGG->SetParError(1,total->GetParError(1));

and I get the integral (works great):

float Ngg=expoGG->Integral(0.1,0.7)/((x2-x1)/nbins);

and the error:

float errNgg=expoGG->IntegralError(0.1,0.7);

and I get “Error in TF1Helper::IntegralError: Last used fitter is not compatible with the current TF1”

and it gives errNgg=0.

why is that?

Thanks for help!
Marek