minimize.cc

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// -*- LSST-C++ -*-
 
/*
 * LSST Data Management System
 * Copyright 2008, 2009, 2010 LSST Corporation.
 *
 * This product includes software developed by the
 * LSST Project (http://www.lsst.org/).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the LSST License Statement and
 * the GNU General Public License along with this program.  If not,
 * see <http://www.lsstcorp.org/LegalNotices/>.
 */
 
/*
 * Definition of member functions for minuit adaptors
 *
 * This file is meant to be included by lsst/afw/math/minimize.h
 */
 
#include <string>
#include <vector>
#include <memory>
 
#include "Minuit2/FunctionMinimum.h"
#include "Minuit2/MnMigrad.h"
#include "Minuit2/MnMinos.h"
 
#include "lsst/log/Log.h"
#include "lsst/afw/math/minimize.h"
 
namespace lsst {
namespace afw {
namespace math {
 
namespace {
/*
 * Minuit wrapper for a function(x)
 */
template <typename ReturnT>
class MinimizerFunctionBase1 : public ROOT::Minuit2::FCNBase {
public:
    explicit MinimizerFunctionBase1(Function1<ReturnT> const &function,
                                    std::vector<double> const &measurementList,
                                    std::vector<double> const &varianceList,
                                    std::vector<double> const &xPositionList, double errorDef);
    MinimizerFunctionBase1(MinimizerFunctionBase1 const &) = default;
    MinimizerFunctionBase1(MinimizerFunctionBase1 &&) = default;
    MinimizerFunctionBase1 &operator=(MinimizerFunctionBase1 const &) = default;
    MinimizerFunctionBase1 &operator=(MinimizerFunctionBase1 &&) = default;
    ~MinimizerFunctionBase1() override = default;
    // Required by ROOT::Minuit2::FCNBase
    double Up() const override { return _errorDef; }
    double operator()(const std::vector<double> &) const override;
 
#if 0  // not used
        inline std::vector<double> getMeasurements() const {return _measurementList;}
        inline std::vector<double> getVariances() const {return _varianceList;}
        inline std::vector<double> getPositions() const {return _xPositionList;}
        inline void setErrorDef(double def) {_errorDef=def;}
#endif
private:
    std::shared_ptr<Function1<ReturnT> > _functionPtr;
    std::vector<double> _measurementList;
    std::vector<double> _varianceList;
    std::vector<double> _xPositionList;
    double _errorDef;
};
 
/*
 * Minuit wrapper for a function(x, y)
 */
template <typename ReturnT>
class MinimizerFunctionBase2 : public ROOT::Minuit2::FCNBase {
public:
    explicit MinimizerFunctionBase2(Function2<ReturnT> const &function,
                                    std::vector<double> const &measurementList,
                                    std::vector<double> const &varianceList,
                                    std::vector<double> const &xPositionList,
                                    std::vector<double> const &yPositionList, double errorDef);
    MinimizerFunctionBase2(MinimizerFunctionBase2 const &) = default;
    MinimizerFunctionBase2(MinimizerFunctionBase2 &&) = default;
    MinimizerFunctionBase2 &operator=(MinimizerFunctionBase2 const &) = default;
    MinimizerFunctionBase2 &operator=(MinimizerFunctionBase2 &&) = default;
    ~MinimizerFunctionBase2() override = default;
    // Required by ROOT::Minuit2::FCNBase
    double Up() const override { return _errorDef; }
    double operator()(const std::vector<double> &par) const override;
 
#if 0  // not used
        inline std::vector<double> getMeasurements() const {return _measurementList;}
        inline std::vector<double> getVariances() const {return _varianceList;}
        inline std::vector<double> getPosition1() const {return _xPositionList;}
        inline std::vector<double> getPosition2() const {return _yPositionList;}
        inline void setErrorDef(double def) {_errorDef=def;}
#endif
private:
    std::shared_ptr<Function2<ReturnT> > _functionPtr;
    std::vector<double> _measurementList;
    std::vector<double> _varianceList;
    std::vector<double> _xPositionList;
    std::vector<double> _yPositionList;
    double _errorDef;
};
}  // namespace
 
template <typename ReturnT>
MinimizerFunctionBase1<ReturnT>::MinimizerFunctionBase1(Function1<ReturnT> const &function,
                                                        std::vector<double> const &measurementList,
                                                        std::vector<double> const &varianceList,
                                                        std::vector<double> const &xPositionList,
                                                        double errorDef)
        : _functionPtr(function.clone()),
          _measurementList(measurementList),
          _varianceList(varianceList),
          _xPositionList(xPositionList),
          _errorDef(errorDef) {}
 
template <typename ReturnT>
MinimizerFunctionBase2<ReturnT>::MinimizerFunctionBase2(Function2<ReturnT> const &function,
                                                        std::vector<double> const &measurementList,
                                                        std::vector<double> const &varianceList,
                                                        std::vector<double> const &xPositionList,
                                                        std::vector<double> const &yPositionList,
                                                        double errorDef)
        : _functionPtr(function.clone()),
          _measurementList(measurementList),
          _varianceList(varianceList),
          _xPositionList(xPositionList),
          _yPositionList(yPositionList),
          _errorDef(errorDef) {}
 
// Only method we need to set up; basically this is a chi^2 routine
template <typename ReturnT>
double MinimizerFunctionBase1<ReturnT>::operator()(const std::vector<double> &par) const {
    // Initialize the function with the fit parameters
    this->_functionPtr->setParameters(par);
 
    double chi2 = 0.0;
    for (unsigned int i = 0; i < this->_measurementList.size(); i++) {
        double resid = (*(this->_functionPtr))(this->_xPositionList[i]) - this->_measurementList[i];
        chi2 += resid * resid / this->_varianceList[i];
    }
 
    return chi2;
}
 
template <typename ReturnT>
double MinimizerFunctionBase2<ReturnT>::operator()(const std::vector<double> &par) const {
    // Initialize the function with the fit parameters
    this->_functionPtr->setParameters(par);
 
    double chi2 = 0.0;
    for (unsigned int i = 0; i < this->_measurementList.size(); i++) {
        double resid = (*(this->_functionPtr))(this->_xPositionList[i], this->_yPositionList[i]) -
                       this->_measurementList[i];
        chi2 += resid * resid / this->_varianceList[i];
    }
 
    return chi2;
}
 
template <typename ReturnT>
FitResults minimize(Function1<ReturnT> const &function, std::vector<double> const &initialParameterList,
                    std::vector<double> const &stepSizeList, std::vector<double> const &measurementList,
                    std::vector<double> const &varianceList, std::vector<double> const &xPositionList,
                    double errorDef) {
    unsigned int const nParameters = function.getNParameters();
    if (initialParameterList.size() != nParameters) {
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError, "initialParameterList is the wrong length");
    }
    if (stepSizeList.size() != nParameters) {
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError, "stepSizeList is the wrong length");
    }
    unsigned int const nMeasurements = measurementList.size();
    if (varianceList.size() != nMeasurements) {
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError, "varianceList is the wrong length");
    }
    if (xPositionList.size() != nMeasurements) {
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError, "xPositionList is the wrong length");
    }
 
    MinimizerFunctionBase1<ReturnT> minimizerFunc(function, measurementList, varianceList, xPositionList,
                                                  errorDef);
 
    ROOT::Minuit2::MnUserParameters fitPar;
    std::vector<std::string> paramNames;
    for (unsigned int i = 0; i < nParameters; ++i) {
        paramNames.push_back((boost::format("p%d") % i).str());
        fitPar.Add(paramNames[i].c_str(), initialParameterList[i], stepSizeList[i]);
    }
 
    ROOT::Minuit2::MnMigrad migrad(minimizerFunc, fitPar);
    ROOT::Minuit2::FunctionMinimum min = migrad();
    ROOT::Minuit2::MnMinos minos(minimizerFunc, min);
 
    FitResults fitResults;
    fitResults.chiSq = min.Fval();
    fitResults.isValid = min.IsValid() && std::isfinite(fitResults.chiSq);
    if (!fitResults.isValid) {
        LOGL_WARN("afw.math.minimize", "Fit failed to converge");
    }
 
    for (unsigned int i = 0; i < nParameters; ++i) {
        fitResults.parameterList.push_back(min.UserState().Value(paramNames[i].c_str()));
        if (fitResults.isValid) {
            fitResults.parameterErrorList.push_back(minos(i));
        } else {
            double e = min.UserState().Error(paramNames[i].c_str());
            std::pair<double, double> ep(-1 * e, e);
            fitResults.parameterErrorList.push_back(ep);
        }
    }
    return fitResults;
}
 
template <typename ReturnT>
FitResults minimize(Function2<ReturnT> const &function, std::vector<double> const &initialParameterList,
                    std::vector<double> const &stepSizeList, std::vector<double> const &measurementList,
                    std::vector<double> const &varianceList, std::vector<double> const &xPositionList,
                    std::vector<double> const &yPositionList, double errorDef) {
    unsigned int const nParameters = function.getNParameters();
    if (initialParameterList.size() != nParameters) {
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError, "initialParameterList is the wrong length");
    }
    if (stepSizeList.size() != nParameters) {
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError, "stepSizeList is the wrong length");
    }
    unsigned int const nMeasurements = measurementList.size();
    if (varianceList.size() != nMeasurements) {
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError, "varianceList is the wrong length");
    }
    if (xPositionList.size() != nMeasurements) {
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError, "xPositionList is the wrong length");
    }
    if (yPositionList.size() != nMeasurements) {
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError, "yPositionList is the wrong length");
    }
 
    MinimizerFunctionBase2<ReturnT> minimizerFunc(function, measurementList, varianceList, xPositionList,
                                                  yPositionList, errorDef);
 
    ROOT::Minuit2::MnUserParameters fitPar;
    std::vector<std::string> paramNames;
    for (unsigned int i = 0; i < nParameters; ++i) {
        paramNames.push_back((boost::format("p%d") % i).str());
        fitPar.Add(paramNames[i].c_str(), initialParameterList[i], stepSizeList[i]);
    }
 
    ROOT::Minuit2::MnMigrad migrad(minimizerFunc, fitPar);
    ROOT::Minuit2::FunctionMinimum min = migrad();
    ROOT::Minuit2::MnMinos minos(minimizerFunc, min);
 
    FitResults fitResults;
    fitResults.chiSq = min.Fval();
    fitResults.isValid = min.IsValid() && std::isfinite(fitResults.chiSq);
    if (!fitResults.isValid) {
        LOGL_WARN("afw.math.minimize", "Fit failed to converge");
    }
 
    for (unsigned int i = 0; i < nParameters; ++i) {
        fitResults.parameterList.push_back(min.UserState().Value(paramNames[i].c_str()));
        if (fitResults.isValid) {
            fitResults.parameterErrorList.push_back(minos(i));
        } else {
            double e = min.UserState().Error(paramNames[i].c_str());
            std::pair<double, double> ep(-1 * e, e);
            fitResults.parameterErrorList.push_back(ep);
        }
    }
    return fitResults;
}
 
// Explicit instantiation
#define NL /* */
#define minimizeFuncs(ReturnT)                                                                      \
    template FitResults minimize(Function1<ReturnT> const &, std::vector<double> const &,           \
                                 std::vector<double> const &, std::vector<double> const &,          \
                                 std::vector<double> const &, std::vector<double> const &, double); \
    NL template FitResults minimize(Function2<ReturnT> const &, std::vector<double> const &,        \
                                    std::vector<double> const &, std::vector<double> const &,       \
                                    std::vector<double> const &, std::vector<double> const &,       \
                                    std::vector<double> const &, double);
 
minimizeFuncs(float) minimizeFuncs(double)
}  // namespace math
}  // namespace afw
}  // namespace lsst