random() [2/2]

Matrix * Matrix::random ( const Ring * R, int r, int c, double fraction_non_zero, int special_type )

static

Definition at line 714 of file matrix.cpp.

{
  bool doing_fraction = false;
  int threshold = 0;
 
  FreeModule *F = R->make_FreeModule(r);
  FreeModule *G = R->make_FreeModule(c);
  MatrixConstructor mat(F, G, nullptr);
 
  // Loop through all selected elements, flip a 'fraction_non_zero' coin, and if
  // non-zero
  // set that element.
 
  if (density != 1.0)
    {
      doing_fraction = true;
      threshold = static_cast<int>(density * 10000);
    }
 
  if (special_type == 0)
    {
      for (int i = 0; i < c; i++)
        for (int j = 0; j < r; j++)
          {
            if (doing_fraction)
              {
                int32_t u = rawRandomInt((int32_t)10000);
                if (u > threshold) continue;
              }
            try {
              mat.set_entry(j, i, R->random());
            } catch (const exc::engine_error& e) {
              ERROR(e.what());
              return nullptr;
            }
          }
    }
  else if (special_type == 1)
    {
      for (int i = 0; i < c; i++)
        {
          int top = (i >= r ? r : i);
          for (int j = 0; j < top; j++)
            {
              if (doing_fraction)
                {
                  int32_t u = rawRandomInt((int32_t)10000);
                  if (u > threshold) continue;
                }
              try {
                mat.set_entry(j, i, R->random());
              } catch (const exc::engine_error& e) {
                ERROR(e.what());
                return nullptr;
              }
            }
        }
    }
  return mat.to_matrix();
}

References ERROR, FreeModule, G, Ring::make_FreeModule(), Matrix(), MatrixConstructor, random(), Ring::random(), rawRandomInt(), MatrixConstructor::set_entry(), and MatrixConstructor::to_matrix().