RtResolutionFromPoints.cxx

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/*
  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
*/
 
#include "MdtCalibData/RtResolutionFromPoints.h"
 
#include "AthenaKernel/getMessageSvc.h"
#include "GaudiKernel/MsgStream.h"
#include "MuonCalibMath/BaseFunctionFitter.h"
#include "MuonCalibMath/ChebyshevPolynomial.h"
#include "MuonCalibMath/PolygonBase.h"
 
using namespace MuonCalib;
 
//*****************************************************************************
 
//::::::::::::::::::::::::
//:: METHOD get_min_max ::
//::::::::::::::::::::::::
void RtResolutionFromPoints::get_min_max(const std::vector<SamplePoint> &sample_points, double &x_min, double &x_max) {
    for (unsigned int k = 0; k < sample_points.size(); k++) {
        if (k == 0) {
            x_min = sample_points[k].x1();
            x_max = x_min;
        }
        if (x_min > sample_points[k].x1()) { x_min = sample_points[k].x1(); }
        if (x_max < sample_points[k].x1()) { x_max = sample_points[k].x1(); }
    }
 
    return;
}
 
//*****************************************************************************
 
//:::::::::::::::::::::::::::::::::::::
//:: METHOD getRtResolutionChebyshev ::
//:::::::::::::::::::::::::::::::::::::
RtResolutionChebyshev RtResolutionFromPoints::getRtResolutionChebyshev(const std::vector<SamplePoint> &sample_points,
                                                                       const unsigned int &order) {
    // VARIABLES //
    MsgStream log(Athena::getMessageSvc(), "RtResolutionChebyshev");
 
    std::vector<double> res_param(order + 3);           // input parameters of RtChebyshev
    BaseFunctionFitter fitter(order + 1);               // Chebyshev fitter
    ChebyshevPolynomial chebyshev;                      // Chebyshev polynomial
    std::vector<SamplePoint> my_points(sample_points);  // copy of the sample to add reduced times
 
    // GET THE MINIMUM AND MAXIMUM TIMES AND CALCULATE REDUCED TIMES //
    get_min_max(sample_points, res_param[0], res_param[1]);
 
    double mean(0.5 * (res_param[1] + res_param[0]));
    double length(res_param[1] - res_param[0]);
    for (unsigned int k = 0; k < my_points.size(); k++) { my_points[k].set_x1(2 * (sample_points[k].x1() - mean) / length); }
 
    // PERFORM A CHEBYSHEV FIT TO THE SAMPLE POINTS //
    if (fitter.fit_parameters(my_points, 1, sample_points.size(), &chebyshev)) {
        log << MSG::WARNING << "Could not determine Chebyshev coefficients." << endmsg;
    }
    for (unsigned int k = 0; k < order + 1; k++) { res_param[k + 2] = fitter.coefficients()[k]; }
 
    // CREATE AN RtChebyshev OBJECT WITH THE CORRECT PARAMETERS //
    RtResolutionChebyshev rt_res_chebyshev(res_param);
 
    return rt_res_chebyshev;
}
 
//*****************************************************************************
 
//::::::::::::::::::::::::::::::::::
//:: METHOD getRtResolutionLookUp ::
//::::::::::::::::::::::::::::::::::
RtResolutionLookUp RtResolutionFromPoints::getRtResolutionLookUp(const std::vector<SamplePoint> &sample_points) {
    // VARIABLES //
    RtResolutionChebyshev res(getRtResolutionChebyshev(sample_points, 8));             // auxiliary resolution-t
    unsigned int nb_points(100);                                                       // number of (r, t) points
    double bin_width((res.tUpper() - res.tLower()) / static_cast<double>(nb_points));  // step size
    std::vector<double> res_param(nb_points + 2);                                      // r-t parameters
 
    // CREATE AN RtRelationLookUp OBJECT WITH THE CORRECT PARAMETERS //
    res_param[0] = res.tLower();
    res_param[1] = bin_width;
    for (unsigned int k = 0; k < nb_points; k++) { res_param[k + 2] = res.resolution(res.tLower() + k * bin_width); }
    RtResolutionLookUp rt_res_relation_look_up(res_param);
 
    return rt_res_relation_look_up;
}