root/Minuit2/MnUserCovariance.h

0001 // @(#)root/minuit2:$Id$
0002 // Authors: M. Winkler, F. James, L. Moneta, A. Zsenei   2003-2005
0003
0004 /**********************************************************************
0005  *                                                                    *
0006  * Copyright (c) 2005 LCG ROOT Math team,  CERN/PH-SFT                *
0007  *                                                                    *
0008  **********************************************************************/
0009
0010 #ifndef ROOT_Minuit2_MnUserCovariance
0011 #define ROOT_Minuit2_MnUserCovariance
0012
0013 #include "Minuit2/MnConfig.h"
0014
0015 #include <ROOT/RSpan.hxx>
0016
0017 #include <vector>
0018 #include <cassert>
0019
0020 namespace ROOT {
0021
0022 namespace Minuit2 {
0023
0024 /**
0025    Class containing the covariance matrix data represented as a vector of
0026    size n*(n+1)/2
0027    Used to hide internal matrix representation to user
0028  */
0029 class MnUserCovariance {
0030
0031 public:
0032    MnUserCovariance() = default;
0033
0034    // safe constructor using std::vector
0035    MnUserCovariance(std::span<const double> data, unsigned int nrow) : fData(data.begin(), data.end()), fNRow(nrow)
0036    {
0037       assert(data.size() == nrow * (nrow + 1) / 2);
0038    }
0039
0040    // unsafe constructor using just a pointer
0041    MnUserCovariance(const double *data, unsigned int nrow)
0042       : fData(std::vector<double>(data, data + nrow * (nrow + 1) / 2)), fNRow(nrow)
0043    {
0044    }
0045
0046    MnUserCovariance(unsigned int n) : fData(std::vector<double>(n * (n + 1) / 2, 0.)), fNRow(n) {}
0047
0048    double operator()(unsigned int row, unsigned int col) const
0049    {
0050       assert(row < fNRow && col < fNRow);
0051       if (row > col)
0052          return fData[col + row * (row + 1) / 2];
0053       else
0054          return fData[row + col * (col + 1) / 2];
0055    }
0056
0057    double &operator()(unsigned int row, unsigned int col)
0058    {
0059       assert(row < fNRow && col < fNRow);
0060       if (row > col)
0061          return fData[col + row * (row + 1) / 2];
0062       else
0063          return fData[row + col * (col + 1) / 2];
0064    }
0065
0066    void Scale(double f)
0067    {
0068       for (unsigned int i = 0; i < fData.size(); i++)
0069          fData[i] *= f;
0070    }
0071
0072    const std::vector<double> &Data() const { return fData; }
0073
0074    unsigned int Nrow() const { return fNRow; }
0075
0076    // VC 7.1 warning: conversion from size_t to unsigned int
0077    unsigned int size() const { return static_cast<unsigned int>(fData.size()); }
0078
0079 private:
0080    std::vector<double> fData;
0081    unsigned int fNRow = 0;
0082 };
0083
0084 } // namespace Minuit2
0085
0086 } // namespace ROOT
0087
0088 #endif // ROOT_Minuit2_MnUserCovariance