DAS::Unfolding::Migrations Namespace Reference

Functions
double	Condition (const unique_ptr< TH2 > &RM)

Function Documentation

Condition()

double DAS::Unfolding::Migrations::Condition

(

const unique_ptr< TH2 > &

RM

)

Condition of the Probability Matrix

Calculates the condition of the probability matrix with the gen binning.

Note: we do not include the miss entries in the normalisation since they are not included in inverted probability matrix

{
    cout << __LINE__ << "\tCalculating condition" << endl;
    const int Nx = RM->GetNbinsX(),
              Ny = RM->GetNbinsY();
 
    auto RMx = unique_ptr<TH1>(RM->ProjectionX("RMx", 0, -1));
 
    // normalisation & condition
    TMatrixD m(Ny,Nx); // unfortunately, we have to swap the axes...
    for (int i = 1; i <= Nx; ++i) {
        double normalisation = RMx->GetBinContent(i);
        if (normalisation > 0)
        for (int j = 1; j <= Ny; ++j)
            m(j-1,i-1) = RM->GetBinContent(i,j) / normalisation;
    }
    TDecompSVD svd(m);
    TVectorD v = svd.GetSig();
 
    double Max = v[0], Min = v[0];
    for(int k = 0; k < Nx; ++k) {
        if (abs(v[k]) < 1e-5) break;
        Min = v[k];
        cout << setw(5) << k << setw(15) << v[k] << setw(15) << Max/Min << '\n';
    }
    if (Min > 0) return Max/Min;
    else         return -numeric_limits<double>::infinity();
}