To find the value of overlapping two histogram

ROOT
1

Hello,

I am plotting two erf functions and corresponding histogram by generating random numbers. I want your help to understand if it is possible to know the overlap ratio or value…

I am writing below how I am plotting the erf functions and its histograms:

TF1 f4(“f4”, “975*TMath::Abs(TMath::Erf((x-1.5)/0.197)-TMath::Erf((x-2.3)/0.197))”, 0.0, 5.4);
f4->Draw();

TF1 f5(“f5”, “975*TMath::Abs(TMath::Erf((x-2.3)/0.197)-TMath::Erf((x-3.1)/0.197))”, 0.0, 5.4);
f5->Draw(“same”);

TH1F *h1 = new TH1F(“h1”, “crystal1”, 60, 1.2, 4.2);
h1->FillRandom(“f4”, 20000);
h1->Draw(“same”);

TH1F *h2 = new TH1F(“h2”, “crystal1”, 60, 1.2, 4.2);
h2->FillRandom(“f5”, 20000);
h2->Draw(“same”);

I will be glad to have some suggestions.

Thank you.

Regards,
Kajal

2

What is an “overlap ratio or value”?

3

Hello,

I want to know the area between the two functions.

Regards,
Kajal

4

I don’t really know what you want to achieve, but try: [code] TF1 f45a(“f45a”, “(f4 < f5) ? f4 : f5”, 0.0, 5.4);
std::cout << f45a.Integral(0.0, 5.4) << std::endl;

TF1 f45b(“f45b”, “(f4 > f5) ? f4 : f5”, 0.0, 5.4);
std::cout << f45b.Integral(0.0, 5.4) << std::endl;
std::cout << f4.Integral(0.0, 5.4) + f5.Integral(0.0, 5.4) - f45a.Integral(0.0, 5.4) << std::endl;

TF1 f45c(“f45c”, “f4 * f5”, 0.0, 5.4);
std::cout << f45c.Integral(0.0, 5.4) << std::endl;

TH1F h12 = ((TH1F)(h1->Clone(“h12”)));
h12->Multiply(h2);
std::cout << h12->Integral(“width”) << std::endl;[/code]

5

Hello Pepe Le Pew,

I just want to calculate the area where the two curves overlap.

Thank you.

Regards,
Kajal
plot.ps (7.49 KB)

6

So, it seems that you want “f45a.Integral(0.0, 5.4)” from my previous post here.

If you want to play the same game with your histograms (i.e. “h1” and “h2”), see: viewtopic.php?f=3&t=22186&p=97166#p97166