ResidualVectorConvergence.hpp

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// This file is part of GQCG-GQCP.
//
// Copyright (C) 2017-2020  the GQCG developers
//
// GQCG-GQCP is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// GQCG-GQCP 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with GQCG-GQCP.  If not, see <http://www.gnu.org/licenses/>.
 
#pragma once
 
 
#include "Mathematical/Algorithm/ConvergenceCriterion.hpp"
 
 
namespace GQCP {
 
 
template <typename _Environment>
class ResidualVectorConvergence:
    public ConvergenceCriterion<_Environment> {
 
public:
    using Environment = _Environment;
 
 
private:
    double threshold;  // the threshold that is used in checking the norm of the residual vectors
 
 
public:
    /*
     *  CONSTRUCTORS
     */
 
    ResidualVectorConvergence(const double threshold = 1.0e-08) :
        threshold {threshold} {}
 
 
    /*
     *  PUBLIC OVERRIDDEN METHODS
     */
 
    std::string description() const override {
        return "A convergence criterion that checks if the norm of each of the residual vectors is smaller than a threshold.";
    }
 
 
    bool isFulfilled(Environment& environment) override {
 
        const auto& R = environment.R;  // the residual vectors
 
        if (R.cols() > 0) {  // if there are residual vectors available
            const auto are_any_values_larger = (R.colwise().norm().array() > this->threshold).any();
            return !are_any_values_larger;
        }
 
        return false;  // there aren't any residual vectors available
    }
};
 
 
}  // namespace GQCP