// Ceres Solver - A fast non-linear least squares minimizer

// Copyright 2015 Google Inc. All rights reserved.

// http://ceres-solver.org/

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are met:

//

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//   this list of conditions and the following disclaimer.

// * Redistributions in binary form must reproduce the above copyright notice,

//   this list of conditions and the following disclaimer in the documentation

//   and/or other materials provided with the distribution.

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//   used to endorse or promote products derived from this software without

//   specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

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// Author: sameeragarwal@google.com (Sameer Agarwal)

#include "ceres/linear_solver.h"

#include "ceres/cgnr_solver.h"

#include "ceres/dense_normal_cholesky_solver.h"

#include "ceres/dense_qr_solver.h"

#include "ceres/iterative_schur_complement_solver.h"

#include "ceres/schur_complement_solver.h"

#include "ceres/dynamic_sparse_normal_cholesky_solver.h"

#include "ceres/sparse_normal_cholesky_solver.h"

#include "ceres/types.h"

#include "glog/logging.h"

namespace ceres {

namespace internal {

LinearSolver::~LinearSolver() {

}

LinearSolverType LinearSolver::LinearSolverForZeroEBlocks(

    LinearSolverType linear_solver_type) {

  if (!IsSchurType(linear_solver_type)) {

    return linear_solver_type;

  }

  if (linear_solver_type == SPARSE_SCHUR) {

    return SPARSE_NORMAL_CHOLESKY;

  }

  if (linear_solver_type == DENSE_SCHUR) {

    // TODO(sameeragarwal): This is probably not a great choice.

    // Ideally, we should have a DENSE_NORMAL_CHOLESKY, that can take

    // a BlockSparseMatrix as input.

    return DENSE_QR;

  }

  if (linear_solver_type == ITERATIVE_SCHUR) {

    return CGNR;

  }

  return linear_solver_type;

}

LinearSolver* LinearSolver::Create(const LinearSolver::Options& options) {

  switch (options.type) {

    case CGNR:

      return new CgnrSolver(options);

    case SPARSE_NORMAL_CHOLESKY:

#if defined(CERES_NO_SUITESPARSE) &&              \

    defined(CERES_NO_CXSPARSE) &&                 \

   !defined(CERES_USE_EIGEN_SPARSE)

      return NULL;

#else

      if (options.dynamic_sparsity) {

        return new DynamicSparseNormalCholeskySolver(options);

      }

      return new SparseNormalCholeskySolver(options);

#endif

    case SPARSE_SCHUR:

#if defined(CERES_NO_SUITESPARSE) &&                 \

    defined(CERES_NO_CXSPARSE) &&                    \

   !defined(CERES_USE_EIGEN_SPARSE)

      return NULL;

#else

      return new SparseSchurComplementSolver(options);

#endif

    case DENSE_SCHUR:

      return new DenseSchurComplementSolver(options);

    case ITERATIVE_SCHUR:

      if (options.use_explicit_schur_complement) {

        return new SparseSchurComplementSolver(options);

      } else {

        return new IterativeSchurComplementSolver(options);

      }

    case DENSE_QR:

      return new DenseQRSolver(options);

    case DENSE_NORMAL_CHOLESKY:

      return new DenseNormalCholeskySolver(options);

    default:

      LOG(FATAL) << "Unknown linear solver type :"

                 << options.type;

      return NULL;  // MSVC doesn't understand that LOG(FATAL) never returns.

  }

}

}  // namespace internal

}  // namespace ceres