CSR_Builder.h

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#ifndef CSR_Builder_included
#define CSR_Builder_included
 
/*! @brief This class is a helper to build CSR stored matrices
 *
 */
class CSR_Builder
{
public:
  CSR_Builder();
  initialize(int nb_lines);
  inline void add_coeff(int line, int column, double coeff);
  build_matrix(Matrice_Bloc&);
protected:
  int nb_lines_;
  // List data contains groups of 2 integers like this:
  //   column, next_index, column, next_index, ...
  //  column is the parameter passed to add_coeff
  //  next_index is the group number of the next coefficient on the same line
  //   or -1 if this is the last coefficient.
  //   if not -1, the next group is
  //       column     = list_data_[2*next_index]
  //       next_index = list_data_[2*next_index+1]
  //   the coefficient is at coeff_data_[next_index]
  //  The first coefficient on line "l" is at list_head[l]
  ArrOfInt list_head_;
  // list_tail_[l] = -1 if the line "l" is empty, otherwise, gives the index
  //   of the last "next_index" on the line (we have list_data_[2*tail+1]=-1)
  ArrOfInt list_tail_;
  ArrOfInt list_data_;
  ArrOfDouble coeff_data_;
};
 
inline void CSR_Builder::add_coeff(int line, int column, double coeff)
{
  assert(line >= 0 && line < nb_lines_);
 
  // We put the new coefficient here:
  const int n = coeff_data_.size_array();
  assert(list_data_.size_array() == n*2); // mixing calls with and without "coeff" is forbidden
  list_data_.resize_array(n*2+2);
  list_data_[n*2] = column;
  list_data_[n*2+1] = -1; // new end of list
  coeff_data_.append_array(coeff);
 
  const int tail = list_tail_[line];
  if (tail < 0)
    {
      // this line is empty, initialize list_head_
      list_head_[line] = n;
    }
  else
    {
      // update the last next_index of the line:
      list_data_[2*tail+1] = n;
    }
  list_tail_[line] = n;
}
 
inline void CSR_Builder::add_coeff(int line, int column)
{
  assert(line >= 0 && line < nb_lines_);
  assert(coeff_data_.size_array() == 0); // mixing calls with and without "coeff" is forbidden
  // We put the new coefficient here:
  const int n = list_data_.size_array() / 2;
  list_data_.resize_array(n*2+2);
  list_data_[n*2] = column;
  list_data_[n*2+1] = -1; // new end of list
 
  const int tail = list_tail_[line];
  if (tail < 0)
    {
      // this line is empty, initialize list_head_
      list_head_[line] = n;
    }
  else
    {
      // update the last next_index of the line:
      list_data_[2*tail+1] = n;
    }
  list_tail_[line] = n;
}
#endif