CostFuncUnweightedLeastSquares.cpp

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// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2018 ISIS Rutherford Appleton Laboratory UKRI,
//   NScD Oak Ridge National Laboratory, European Spallation Source,
//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
#include "MantidCurveFitting/CostFunctions/CostFuncUnweightedLeastSquares.h"
 
#include "MantidKernel/Logger.h"
#include <cmath>
 
namespace Mantid::CurveFitting::CostFunctions {
 
namespace {
Kernel::Logger g_log("CostFuncUnweightedLeastSquares");
} // namespace
 
DECLARE_COSTFUNCTION(CostFuncUnweightedLeastSquares, Unweighted least squares)
 
CostFuncUnweightedLeastSquares::CostFuncUnweightedLeastSquares() : CostFuncLeastSquares() {}
 
void CostFuncUnweightedLeastSquares::calActiveCovarianceMatrix(EigenMatrix &covar, double epsrel) {
  CostFuncLeastSquares::calActiveCovarianceMatrix(covar, epsrel);
 
  double variance = getResidualVariance();
  covar *= variance;
 
  if (g_log.is(Kernel::Logger::Priority::PRIO_DEBUG)) {
    g_log.debug() << "== Final covariance matrix (H^-1) ==\n";
 
    std::ios::fmtflags prevState = g_log.debug().flags();
    g_log.debug() << std::left << std::fixed;
 
    for (size_t i = 0; i < covar.size1(); ++i) {
      for (size_t j = 0; j < covar.size2(); ++j) {
        g_log.debug() << std::setw(10);
        g_log.debug() << covar.get(i, j) << "  ";
      }
      g_log.debug() << '\n';
    }
    g_log.debug().flags(prevState);
  }
}
 
std::vector<double> CostFuncUnweightedLeastSquares::getFitWeights(API::FunctionValues_sptr values) const {
  std::vector<double> weights(values->size());
  for (size_t i = 0; i < weights.size(); ++i) {
    weights[i] = values->getFitWeight(i) != 0 ? 1 : 0;
  }
 
  return weights;
}
 
double CostFuncUnweightedLeastSquares::getResidualVariance() const {
  if (!m_values || m_values->size() == 0) {
    return 0;
  }
 
  double sum = 0.0;
  for (size_t i = 0; i < m_values->size(); ++i) {
    double difference = m_values->getCalculated(i) - m_values->getFitData(i);
    sum += difference * difference;
  }
 
  auto degreesOfFreedom = static_cast<double>(m_values->size() - nParams());
  double residualVariance = sum / degreesOfFreedom;
 
  if (g_log.is(Kernel::Logger::Priority::PRIO_DEBUG)) {
    g_log.debug() << "== Statistics of residuals ==\n";
    std::ios::fmtflags prevState = g_log.debug().flags();
    g_log.debug() << std::left << std::fixed << std::setw(10);
    g_log.debug() << "Residual sum of squares: " << sum << '\n';
    g_log.debug() << "Residual variance: " << residualVariance << '\n';
    g_log.debug() << "Residual standard deviation: " << sqrt(residualVariance) << '\n';
    g_log.debug() << "Degrees of freedom: " << static_cast<size_t>(degreesOfFreedom) << '\n';
    g_log.debug() << "Number of observations: " << m_values->size() << '\n';
    g_log.debug().flags(prevState);
  }
 
  return residualVariance;
}
 
} // namespace Mantid::CurveFitting::CostFunctions