#include "TF1.h"
#include "TH1.h"

int  fit511(TH1 *h){
TF1 *fb2 = new TF1("fb2","gaus(6)+gaus(0)+[3]*TMath::Erfc((x-[4])/[5])",0,10); 
fb2->SetParameters(20,2300,30,10,1600,100,15000,100,6); 
fb2->Draw();
fb2->SetLineColor(kRed);
fb2->SetParLimits(1, 2000, 3500);// peak1
fb2->SetParLimits(2, 20, 200);  // mean1
fb2->SetParLimits(4, 1300, 2000); // peak2
fb2->SetParLimits(5, 5, 250);   // sigma erf
fb2->SetParLimits(7, 50, 150);  //peak3 bgr
fb2->SetParLimits(8, 0, 20);    // sigma brg
h->Fit(fb2,"","",100,3500);
float e1=fabs(fb2->GetParameter(1));
float de=fabs(fb2->GetParameter(2));
float e0=fabs(fb2->GetParameter(7));
char label[1256];
sprintf(label,"Peak1=%5.0f  Peak2=%5.0f  Sigma=%5.1f Resolution FWHM=%5.3f;ADC;N", e1,e0,de,de/(e1-e0)*2.35);
h->SetTitle(label);

return 0;
}