The initial values to the fitting parameters assigned properly using...

The initial values to the fitting parameters assigned properly using FindLastBinAbove() and GetBinCenter().

gain_measurement.cpp

@@ -20,9 +20,25 @@ void gain_measurement()
 
 
   modified_erf->SetParNames("constant","mean","noise");
-  modified_erf->SetParameter(1,hist_255->GetMean());
-  modified_erf->SetParameter(2,hist_255->GetRMS());
-  modified_erf->SetParLimits(0,200,250.0);
+
+  // Seeting the initial values for the fit parameters
+
+  
+  modified_erf->SetParameter(0,200.0);
+
+  double lastbin1 = hist_255->FindLastBinAbove(200);
+  double mean = hist_255->GetBinCenter(lastbin1);
+  cout<<"The initial mean value assigned is : "<<mean<<std::endl;
+  modified_erf->SetParameter(1,mean);
+
+  double lastbin2 = hist_255->FindLastBinAbove(150);
+  double lastbin3 = hist_255->FindLastBinAbove(50);
+  double sigma = lastbin3 -lastbin2;
+  cout<<"The initial noise assigned is :"<<sigma<<std::endl;
+  modified_erf->SetParameter(2,sigma);
+
+  //Fitting histogram
+  
   modified_erf->SetLineWidth(2);
   modified_erf->SetLineColor(2);