How to fit a unsymmetrical gaus distributing?


I want to fit a TGraph which have a unsymmetrical gaus distributing. This TGraph have the same “constant” and “mean”, but have different “sigma” less than “mean” and more than “mean”.
Would you help me? Thank you!!

6.8 [/b]

see example below
root > .x DoubleGauss.C


Double_t mydgauss(Double_t *x, Double_t *par) { Double_t arg1 =(x[0]-par[1])/par[2]; Double_t arg2 =(x[0]-par[1])/par[3]; Double_t r1 = TMath::Exp(-arg1*arg1); Double_t r2 = TMath::Exp(-arg2*arg2); return par[0]*(r1+r2); } void DoubleGauss() { TF1 *f1 = new TF1("f1",mydgauss,-3,5,4); f1->SetParameters(1,0,1,2); TH1F *h1 = new TH1F("h1","double gauss",100,-3,5); h1->FillRandom("f1",10000); h1->Fit(f1); h1->Draw(); }

Thank you very much!!