sparse_block_matrix_diagonal.h

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// g2o - General Graph Optimization
// Copyright (C) 2011 R. Kuemmerle, G. Grisetti, W. Burgard
// All rights reserved.
//
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//
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#ifndef G2O_SPARSE_BLOCK_MATRIX_DIAGONAL_H
#define G2O_SPARSE_BLOCK_MATRIX_DIAGONAL_H
 
#include <Eigen/Core>
#include <vector>
 
#include "g2o/config.h"
#include "matrix_operations.h"
 
namespace g2o {

template <class MatrixType>
class SparseBlockMatrixDiagonal {
 public:
  typedef MatrixType SparseMatrixBlock;

  int cols() const { return _blockIndices.size() ? _blockIndices.back() : 0; }
  int rows() const { return _blockIndices.size() ? _blockIndices.back() : 0; }
 
  using DiagonalVector = std::vector<MatrixType>;
 
  SparseBlockMatrixDiagonal(const std::vector<int>& blockIndices)
      : _blockIndices(blockIndices) {}

  inline int dimOfBlock(int r) const {
    return r ? _blockIndices[r] - _blockIndices[r - 1] : _blockIndices[0];
  }

  inline int baseOfBlock(int r) const { return r ? _blockIndices[r - 1] : 0; }

  const DiagonalVector& diagonal() const { return _diagonal; }
  DiagonalVector& diagonal() { return _diagonal; }

  const std::vector<int>& blockIndices() const { return _blockIndices; }
 
  void multiply(double*& dest, const double* src) const {
    int destSize = cols();
    if (!dest) {
      dest = new double[destSize];
      memset(dest, 0, destSize * sizeof(double));
    }
 
    // map the memory by Eigen
    Eigen::Map<VectorX> destVec(dest, destSize);
    Eigen::Map<const VectorX> srcVec(src, rows());
 
#ifdef G2O_OPENMP
#pragma omp parallel for default(shared) schedule(dynamic, 10)
#endif
    for (int i = 0; i < static_cast<int>(_diagonal.size()); ++i) {
      int destOffset = baseOfBlock(i);
      int srcOffset = destOffset;
      const SparseMatrixBlock& A = _diagonal[i];
      // destVec += *A.transpose() * srcVec (according to the sub-vector parts)
      internal::template axpy<SparseMatrixBlock>(A, srcVec, srcOffset, destVec,
                                                 destOffset);
    }
  }
 
 protected:
  const std::vector<int>& _blockIndices;  
  DiagonalVector _diagonal;
};
 
}  // namespace g2o
 
#endif