// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2013 Google Inc. All rights reserved.
// http://code.google.com/p/ceres-solver/
//
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// Author: sameeragarwal@google.com (Sameer Agarwal)

#include <limits>
#include <vector>

#include "ceres/block_random_access_diagonal_matrix.h"
#include "ceres/internal/eigen.h"
#include "glog/logging.h"
#include "gtest/gtest.h"

namespace ceres {
namespace internal {

TEST(BlockRandomAccessDiagonalMatrix, GetCell) {
  vector<int> blocks;
  blocks.push_back(3);
  blocks.push_back(4);
  blocks.push_back(5);
  const int num_rows = 3 + 4 + 5;
  const int num_nonzeros =  3 * 3 + 4 * 4 + 5 * 5;

  BlockRandomAccessDiagonalMatrix m(blocks);
  EXPECT_EQ(m.num_rows(), num_rows);
  EXPECT_EQ(m.num_cols(), num_rows);

  for (int i = 0; i < blocks.size(); ++i) {
    const int row_block_id = i;
    int col_block_id;
    int row;
    int col;
    int row_stride;
    int col_stride;

    for (int j = 0; j < blocks.size(); ++j) {
      col_block_id = j;
      CellInfo* cell =  m.GetCell(row_block_id, col_block_id,
                                  &row, &col,
                                  &row_stride, &col_stride);
      // Off diagonal entries are not present.
      if (i != j) {
        EXPECT_TRUE(cell == NULL);
        continue;
      }

      EXPECT_TRUE(cell != NULL);
      EXPECT_EQ(row, 0);
      EXPECT_EQ(col, 0);
      EXPECT_EQ(row_stride, blocks[row_block_id]);
      EXPECT_EQ(col_stride, blocks[col_block_id]);

      // Write into the block
      MatrixRef(cell->values, row_stride, col_stride).block(
          row, col, blocks[row_block_id], blocks[col_block_id]) =
          (row_block_id + 1) * (col_block_id +1) *
          Matrix::Ones(blocks[row_block_id], blocks[col_block_id]);
    }
  }

  const TripletSparseMatrix* tsm = m.matrix();
  EXPECT_EQ(tsm->num_nonzeros(), num_nonzeros);
  EXPECT_EQ(tsm->max_num_nonzeros(), num_nonzeros);

  Matrix dense;
  tsm->ToDenseMatrix(&dense);

  double kTolerance = 1e-14;

  // (0,0)
  EXPECT_NEAR((dense.block(0, 0, 3, 3) - Matrix::Ones(3, 3)).norm(),
              0.0,
              kTolerance);

  // (1,1)
  EXPECT_NEAR((dense.block(3, 3, 4, 4) - 2 * 2 * Matrix::Ones(4, 4)).norm(),
              0.0,
              kTolerance);

  // (1,1)
  EXPECT_NEAR((dense.block(7, 7, 5, 5) - 3 * 3 * Matrix::Ones(5, 5)).norm(),
              0.0,
              kTolerance);

  // There is nothing else in the matrix besides these four blocks.
  EXPECT_NEAR(dense.norm(), sqrt(9.0 + 16. * 16. + 81.0 * 25.), kTolerance);
}

}  // namespace internal
}  // namespace ceres