[Dune] [Dune-Commit] dune-common r5072 - trunk/common

[Markus Blatt]

Hi,

On Tue, Feb 05, 2008 at 06:26:45PM +0100, robertk at dune-project.org wrote:
> 
> Modified: trunk/common/fmatrix.hh
> ===================================================================
> --- trunk/common/fmatrix.hh	2008-02-05 15:57:01 UTC (rev 5071)
> +++ trunk/common/fmatrix.hh	2008-02-05 17:26:45 UTC (rev 5072)
> @@ -241,9 +241,10 @@
>  	  if (x.N()!=M()) DUNE_THROW(FMatrixError,"index out of range");
>  	  if (y.N()!=N()) DUNE_THROW(FMatrixError,"index out of range");
>  #endif
> -          for (size_type i=0; i<n; i++)
> -              for (size_type j=0; j<m; j++)
> -                  y[i] = (*this)[i][j] * x[j];
> +    for (size_type i=0; i<n; ++i)
> +    {
> +      y[i] = (*this)[i] * x;
> +    }
>  	}


Doesn't this create a temporary FieldVector?

Anyway I would prefer two loops and setting y[i]=0 and then adding up
the multiplication result:

for (size_type i=0; i<n; ++i){
    y[i]=0;
    for (size_type j=0; j<n; ++j)
      y[i] += (*this)[i][j]*x[j]
}

Cheers,

Markus