Re: Mark a matrix "upper" in a oct-file

[David Bateman]

> Le 5 sept. 2014 à 13:56, Marco Caliari <address@hidden> a écrit :
> 
> 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)?
> 

Look at the matrix_type function for how to mark the matrix as upper. However, 
marking it as such is only useful at this point for the solve function or slash 
operators. 

D.


> Thanks,
> 
> Marco
> 
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