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Subject: [ublas] Matrix multiplication performance
From: palik imre (imre_palik_at_[hidden])
Date: 2016-01-17 15:23:16

Hi all,

It seems that the matrix multiplication in ublas ends up with the trivial algorithm. On my machine, even the following function outperforms it for square matrices bigger than 173*173 (by a huge margin for matrices bigger than 190*190), while not performing considerably worse for smaller matrices:

matmul_byrow(const matrix<double> &lhs, const matrix<double> &rhs)
  assert(lhs.size2() == rhs.size1());
  matrix<double> rv(lhs.size1(), rhs.size2());
  matrix<double> r = trans(rhs);
  for (unsigned c = 0; c < rhs.size2(); c++)
      matrix_column<matrix<double> > out(rv, c);
      matrix_row<matrix<double> > in(r, c);
      out = prod(lhs, in);
  return rv;

Is there anybody working on improving the matrix multiplication performance?

If not, then I can try to find some spare cycles ...


Imre Palik