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

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

#include "ceres/block_jacobi_preconditioner.h"

#include <vector>

#include "ceres/block_random_access_diagonal_matrix.h"

#include "ceres/linear_least_squares_problems.h"

#include "ceres/block_sparse_matrix.h"

#include "ceres/internal/scoped_ptr.h"

#include "gtest/gtest.h"

#include "Eigen/Dense"

namespace ceres {

namespace internal {

class BlockJacobiPreconditionerTest : public ::testing::Test {

 protected:

  void SetUpFromProblemId(int problem_id) {

    scoped_ptr<LinearLeastSquaresProblem> problem(

        CreateLinearLeastSquaresProblemFromId(problem_id));

    CHECK_NOTNULL(problem.get());

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

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

    Matrix dense_a;

    A->ToDenseMatrix(&dense_a);

    dense_ata = dense_a.transpose() * dense_a;

    dense_ata += VectorRef(D.get(), A->num_cols())

        .array().square().matrix().asDiagonal();

  }

  void VerifyDiagonalBlocks(const int problem_id) {

    SetUpFromProblemId(problem_id);

    BlockJacobiPreconditioner pre(*A);

    pre.Update(*A, D.get());

    BlockRandomAccessDiagonalMatrix* m =

        const_cast<BlockRandomAccessDiagonalMatrix*>(&pre.matrix());

    EXPECT_EQ(m->num_rows(), A->num_cols());

    EXPECT_EQ(m->num_cols(), A->num_cols());

    const CompressedRowBlockStructure* bs = A->block_structure();

    for (int i = 0; i < bs->cols.size(); ++i) {

      const int block_size = bs->cols[i].size;

      int r, c, row_stride, col_stride;

      CellInfo* cell_info = m->GetCell(i, i,

                                       &r, &c,

                                       &row_stride, &col_stride);

      MatrixRef m(cell_info->values, row_stride, col_stride);

      Matrix actual_block_inverse = m.block(r, c, block_size, block_size);

      Matrix expected_block = dense_ata.block(bs->cols[i].position,

                                              bs->cols[i].position,

                                              block_size,

                                              block_size);

      const double residual = (actual_block_inverse * expected_block -

                               Matrix::Identity(block_size, block_size)).norm();

      EXPECT_NEAR(residual, 0.0, 1e-12) << "Block: " << i;

    }

  }

  scoped_ptr<BlockSparseMatrix> A;

  scoped_array<double> D;

  Matrix dense_ata;

};

TEST_F(BlockJacobiPreconditionerTest, SmallProblem) {

  VerifyDiagonalBlocks(2);

}

TEST_F(BlockJacobiPreconditionerTest, LargeProblem) {

  VerifyDiagonalBlocks(3);

}

}  // namespace internal

}  // namespace ceres