# Histogram multiply and division

Hello,

I need to calculate the efficiency using bin by bin (2D).I used following equation and code it as follows.

`````` Efficiency=(h2_pim_4fold_exc)/(h2_pim_3fold_exc- normalized bgnd);
normlaized_bgnd= (h2_pim_3fold_bgnd/h2_pim_4fold_bgnd_notexc)* h2_pim_4fold_exc_notexc;
``````

I am really disappointed the answer I got.Is something wrong with my code(sorry for the confused names for the histograms)

``````{

//f_bgd= (Integrate 3-fold)/(Integrated 4-fold !Exc) in bgnd region
TH2F *f_bgnd=(TH2F*)h2_pim_3fold_bgnd->Clone("f_bgnd");
f_bgnd->Divide(h2_pim_4fold_bgnd_notExc);

//     normalized bgnd = f_bgd * (4-fold !Exc integrated over "exclusive" window of missing pi- M2)
TH2F* Normalized_bgnd=(TH2F*) f_bgnd->Clone("Normalized_bgnd");
Normalized_bgnd->Multiply(h2_pim_4fold_exc_notExc);

//   (h2_pim_3fold_exc- normalized bgnd)
TH2F* Neg_Normalized_bgnd= (TH2F*) Normalized_bgnd->Clone("Neg_Normalized_bgnd");
Neg_Normalized_bgnd->Scale(-1);

// Efficiency=(h2_pim_4fold_exc)/(h2_pim_3fold_exc- normalized bgnd);
TH2F * Efficiency= (TH2F*) h2_pim_4fold_exc->Clone("Efficiency");
Efficiency->Divide(h2_pim_4fold_exc,h2_pim_3fold_exc);

Efficiency->SetMarkerSize(1.5);
Efficiency->Draw("text30");

}

``````

Any hint would be greatly appreciated.

Thanks

ROOT Version: Not Provided
Platform: Not Provided
Compiler: Not Provided

The code seems good to me and it seems to follow the operations you have shown above.
What is wrong with the result you have ?

Hello moneto,

The following two ways gave me different answers.Which one is correct?

``````TH2F * Normalized_bgnd=(TH2F*)h2_pim_3fold_exc->Clone("Normalized_bgnd");
Normalized_bgnd->Divide(h2_pim_4fold_bgnd_notExc);
Normalized_bgnd->Multiply(h2_pim_4fold_exc_notExc);
``````
``````//f_bgd= (Integrate 3-fold)/(Integrated 4-fold !Exc) in bgnd region
TH2F *f_bgnd=(TH2F*)h2_pim_3fold_bgnd->Clone("f_bgnd");
f_bgnd->Divide(h2_pim_4fold_bgnd_notExc);

//     normalized bgnd = f_bgd * (4-fold !Exc integrated over "exclusive" window of missing pi- M2)
TH2F* Normalized_bgnd=(TH2F*) f_bgnd->Clone("Normalized_bgnd");
Normalized_bgnd->Multiply(h2_pim_4fold_exc_notExc);

``````

Thanks

Hello,

Can someone help me to do Efficiency calulation using TEfficiency?

``````{

//f_bgd= (Integrate 3-fold)/(Integrated 4-fold !Exc) in bgnd region
TH2F *f_bgnd=(TH2F*)h2_pim_3fold_bgnd->Clone("f_bgnd");
f_bgnd->Divide(h2_pim_4fold_bgnd_notExc);

//     normalized bgnd = f_bgd * (4-fold !Exc integrated over "exclusive" window of missing pi- M2)
TH2F* Normalized_bgnd=(TH2F*) f_bgnd->Clone("Normalized_bgnd");
Normalized_bgnd->Multiply(h2_pim_4fold_exc_notExc);

//   (h2_pim_3fold_exc- normalized bgnd)
TH2F* Neg_Normalized_bgnd= (TH2F*) Normalized_bgnd->Clone("Neg_Normalized_bgnd");
Neg_Normalized_bgnd->Scale(-1);

// Efficiency=(h2_pim_4fold_exc)/(h2_pim_3fold_exc- normalized bgnd);
TH2F * Efficiency= (TH2F*) h2_pim_4fold_exc->Clone("Efficiency");
Efficiency->Divide(h2_pim_4fold_exc,h2_pim_3fold_exc);

Efficiency->SetMarkerSize(1.5);
Efficiency->Draw("text30");

}

``````

Thanks
Dil

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