JacobiRotation.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 "Utilities/Eigen.hpp"
 
#include <cstdlib>
#include <ostream>
 
 
namespace GQCP {
 
 
class JacobiRotation {
private:
    // The index of the first rotated orbital. (p > q)
    size_t m_p;
 
    // The index of the second rotated orbital. (p > q)
    size_t m_q;
 
    // The angle of rotation, in radians.
    double m_angle;
 
 
public:
    /*
     *  MARK: Constructors
     */
 
    JacobiRotation(const size_t p, const size_t q, const double angle);
 
    JacobiRotation();
 
 
    /*
     *  MARK: Operators
     */
 
    friend std::ostream& operator<<(std::ostream& os, const JacobiRotation& jacobi_rotation);
 
 
    /*
     *  MARK: General information
     */
 
    double angle() const { return this->m_angle; }
 
    size_t p() const { return this->m_p; }
 
    size_t q() const { return this->m_q; }
 
 
    /*
     *  MARK: Conversions
     */
 
    Eigen::JacobiRotation<double> Eigen() const { return Eigen::JacobiRotation<double> {std::cos(this->angle()), std::sin(this->angle())}; }
};
 
 
}  // namespace GQCP