LLSSolver.h

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// Copyright (C) 2020 ASTRON (Netherlands Institute for Radio Astronomy)
// SPDX-License-Identifier: GPL-3.0-or-later
 
#ifndef DDECAL_LLS_SOLVER_H
#define DDECAL_LLS_SOLVER_H
 
#include <complex>
#include <memory>
#include <utility>
#include <vector>
 
namespace dp3 {
namespace ddecal {
 
enum class LLSSolverType { QR, SVD, NORMAL_EQUATIONS };
 
class LLSSolver {
 public:
  using complex = std::complex<float>;
  LLSSolver(int m, int n, int nrhs) : m_(m), n_(n), nrhs_(nrhs) {}
 
  virtual ~LLSSolver() {}
 
  virtual bool Solve(complex* a, complex* b) = 0;
  virtual bool Solve(complex* a, complex* b,
                     [[maybe_unused]] complex* initial_value) {
    return Solve(a, b);
  }  // can use initial guess x
 
  static std::unique_ptr<LLSSolver> Make(LLSSolverType lss_type, int m, int n,
                                         int nrhs);
 
  static LLSSolverType ParseType(const std::string& solver);
 
 protected:
  int m_;     // number of rows in matrix A
  int n_;     // number of columns in matrix A
  int nrhs_;  // number of columns in vector b
};
 
}  // namespace ddecal
}  // namespace dp3
 
#endif