Dear Root users
I am new on root and i want to get FWTM for skewed Gaussian. I found the crystal ball function to be a good fit for my histogram which has a tail at low energies. For normal Gaussian, FWHM = 2.35sigma and FWTM= 4.29sigma. However this is not the case for a skewed Gaussian as it has a tail. Is there way to get the FWTM of skewed Gaussian?
My simple code now looks like this:
void draw(){
TF1 *g9 = new TF1(“g9”, “crystalball”);
g9->SetParameters(1000,2664,3,1,2);
h1->Draw();
h1->Fit(“g9”,"","",2650,2675);
//int xmin = h1->GetMinimum(2650);
//int xmax = h1->GetMaximum(2675)
int bin1 = h1->FindFirstBinAbove(h1->GetMaximum()/10);
int bin2 = h1->FindLastBinAbove(h1->GetMaximum()/10);
double fwhm = h1->GetBinCenter(bin2) - h1->GetBinCenter(bin1);
cout << endl << "FWTM = " << fwtm << endl;
}
This is not true because sigma at 10% of my peak will be different on both side of the mean, because the low energy side has a tail while the high energy side has normal Gaussian shape.
You ideas will be highly appreciated.
Lucky