DiagonalizerFeast.hpp

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// SPDX-FileCopyrightText: 2024 Pairinteraction Developers
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#pragma once
 
#include "pairinteraction/enums/FloatType.hpp"
#include "pairinteraction/interfaces/DiagonalizerInterface.hpp"
#include "pairinteraction/utils/eigen_assertion.hpp"
 
#include <Eigen/SparseCore>
#include <complex>
#include <optional>
 
namespace pairinteraction {
template <typename Scalar>
class DiagonalizerFeast : public DiagonalizerInterface<Scalar> {
public:
    using typename DiagonalizerInterface<Scalar>::real_t;
 
    DiagonalizerFeast(int m0, FloatType float_type = FloatType::FLOAT64);
    EigenSystemH<Scalar> eigh(const Eigen::SparseMatrix<Scalar, Eigen::RowMajor> &matrix,
                              double rtol) const override;
    EigenSystemH<Scalar> eigh(const Eigen::SparseMatrix<Scalar, Eigen::RowMajor> &matrix,
                              std::optional<real_t> min_eigenvalue,
                              std::optional<real_t> max_eigenvalue, double rtol) const override;
 
private:
    int m0;
    template <typename ScalarLim>
    EigenSystemH<Scalar> dispatch_eigh(const Eigen::SparseMatrix<Scalar, Eigen::RowMajor> &matrix,
                                       real_t min_eigenvalue, real_t max_eigenvalue,
                                       double rtol) const;
};
 
extern template class DiagonalizerFeast<double>;
extern template class DiagonalizerFeast<std::complex<double>>;
} // namespace pairinteraction