csr_sparse.hpp

Go to the documentation of this file.

//    Copyright 2023 Jij Inc.
 
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
 
//        http://www.apache.org/licenses/LICENSE-2.0
 
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
 
#pragma once
 
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <type_traits>
#include <unordered_map>
#include <utility>
 
#include "openjij/graph/graph.hpp"
 
#include <Eigen/Sparse>
 
#include "openjij/utility/disable_eigen_warning.hpp"
 
namespace openjij {
namespace graph {
 
template <typename FloatType> class CSRSparse : public Graph {
  static_assert(std::is_floating_point<FloatType>::value,
                "FloatType must be floating-point type.");
 
public:
  using Interactions =
      Eigen::SparseMatrix<FloatType, Eigen::RowMajor>;
 
  using value_type = FloatType;
 
private:
  Interactions _J;
 
public:
 
  explicit CSRSparse(const Interactions &interaction): Graph(interaction.rows()-1) {
    if (interaction.rows() != interaction.cols()) {
      std::runtime_error("interaction.rows() != interaction.cols()");
    }
    _J = interaction.template selfadjointView<Eigen::Upper>();
  } 
 
  CSRSparse(const CSRSparse<FloatType> &) = default;
 
  CSRSparse(CSRSparse<FloatType> &&) = default;
 
  FloatType calc_energy(const Spins &spins) const {
    return this->energy(spins);
  }
 
  FloatType calc_energy(const Eigen::Matrix<FloatType, Eigen::Dynamic, 1,
                                            Eigen::ColMajor> &spins) const {
    return this->energy(spins);
  }
 
  FloatType energy(const Spins &spins) const {
    if (spins.size() != this->get_num_spins()) {
      throw std::out_of_range("Out of range in energy in CSRSparse graph.");
    }
 
    using Vec = Eigen::Matrix<FloatType, Eigen::Dynamic, 1, Eigen::ColMajor>;
    Vec s(get_num_spins() + 1);
    for (size_t i = 0; i < spins.size(); i++) {
      s(i) = spins[i];
    }
    s(get_num_spins()) = 1;
 
    // the energy must be consistent with BinaryQuadraticModel.
    return (s.transpose() *
            (_J.template triangularView<Eigen::Upper>() * s))(0, 0) -
           1;
  }
 
  FloatType energy(const Eigen::Matrix<FloatType, Eigen::Dynamic, 1,
                                       Eigen::ColMajor> &spins) const {
    graph::Spins temp_spins(get_num_spins());
    for (size_t i = 0; i < temp_spins.size(); i++) {
      temp_spins[i] = spins(i);
    }
    return energy(temp_spins);
  }
 
  const Interactions get_interactions() const {
    return this->_J.template selfadjointView<Eigen::Upper>();
  }
};
} // namespace graph
} // namespace openjij