// 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:

//

// * Redistributions of source code must retain the above copyright notice,

//   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.

// * Neither the name of Google Inc. nor the names of its contributors may be

//   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

// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

// POSSIBILITY OF SUCH DAMAGE.

//

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

//

// TODO(sameeragarwal): Add support for larger, more complicated and

// poorly conditioned problems both for correctness testing as well as

// benchmarking.

#include "ceres/iterative_schur_complement_solver.h"

#include <cstddef>

#include "Eigen/Dense"

#include "ceres/block_random_access_dense_matrix.h"

#include "ceres/block_sparse_matrix.h"

#include "ceres/casts.h"

#include "ceres/internal/eigen.h"

#include "ceres/internal/scoped_ptr.h"

#include "ceres/linear_least_squares_problems.h"

#include "ceres/linear_solver.h"

#include "ceres/schur_eliminator.h"

#include "ceres/triplet_sparse_matrix.h"

#include "ceres/types.h"

#include "glog/logging.h"

#include "gtest/gtest.h"

namespace ceres {

namespace internal {

using testing::AssertionResult;

const double kEpsilon = 1e-14;

class IterativeSchurComplementSolverTest : public ::testing::Test {

 protected :

  void SetUpProblem(int problem_id) {

    scoped_ptr<LinearLeastSquaresProblem> problem(

        CreateLinearLeastSquaresProblemFromId(problem_id));

    CHECK_NOTNULL(problem.get());

    A_.reset(down_cast<BlockSparseMatrix*>(problem->A.release()));

    b_.reset(problem->b.release());

    D_.reset(problem->D.release());

    num_cols_ = A_->num_cols();

    num_rows_ = A_->num_rows();

    num_eliminate_blocks_ = problem->num_eliminate_blocks;

  }

  AssertionResult TestSolver(double* D) {

    TripletSparseMatrix triplet_A(A_->num_rows(),

                                  A_->num_cols(),

                                  A_->num_nonzeros());

    A_->ToTripletSparseMatrix(&triplet_A);

    DenseSparseMatrix dense_A(triplet_A);

    LinearSolver::Options options;

    options.type = DENSE_QR;

    scoped_ptr<LinearSolver> qr(LinearSolver::Create(options));

    LinearSolver::PerSolveOptions per_solve_options;

    per_solve_options.D = D;

    Vector reference_solution(num_cols_);

    qr->Solve(&dense_A, b_.get(), per_solve_options, reference_solution.data());

    options.elimination_groups.push_back(num_eliminate_blocks_);

    options.elimination_groups.push_back(0);

    options.max_num_iterations = num_cols_;

    options.preconditioner_type = SCHUR_JACOBI;

    IterativeSchurComplementSolver isc(options);

    Vector isc_sol(num_cols_);

    per_solve_options.r_tolerance  = 1e-12;

    isc.Solve(A_.get(), b_.get(), per_solve_options, isc_sol.data());

    double diff = (isc_sol - reference_solution).norm();

    if (diff < kEpsilon) {

      return testing::AssertionSuccess();

    } else {

      return testing::AssertionFailure()

          << "The reference solution differs from the ITERATIVE_SCHUR"

          << " solution by " << diff << " which is more than " << kEpsilon;

    }

  }

  int num_rows_;

  int num_cols_;

  int num_eliminate_blocks_;

  scoped_ptr<BlockSparseMatrix> A_;

  scoped_array<double> b_;

  scoped_array<double> D_;

};

TEST_F(IterativeSchurComplementSolverTest, NormalProblem) {

  SetUpProblem(2);

  EXPECT_TRUE(TestSolver(NULL));

  EXPECT_TRUE(TestSolver(D_.get()));

}

TEST_F(IterativeSchurComplementSolverTest, ProblemWithNoFBlocks) {

  SetUpProblem(3);

  EXPECT_TRUE(TestSolver(NULL));

  EXPECT_TRUE(TestSolver(D_.get()));

}

}  // namespace internal

}  // namespace ceres