Mark a matrix "upper" in a oct-file

[Marco Caliari]

Dear all,

I have to take the upper triangular part of a matrix in a oct-file. Later, 
I have to perform RowVector-Matrix products with it. This is my code

// given Matrix F(m,m)
// take the upper triangular part
for (octave_idx_type j = 0; j < m; j++)
    {
      for (octave_idx_type i = j+1; i < m; i++)
        F(i,j) = 0.0;
    }
  RowVector d = F.row(0);
// make RowVector-matrix products
  for (octave_idx_type i = 0; i < s-1; i++)
    d = d * F;

My question is: if I mark the matrix "upper" (but do not know how to do 
it), is the RowVector-Matrix product faster (for instance BLAS dtrmv is 
used instead of general dgemv)?

Thanks,

Marco