[Dune] [Dune-Commit] dune-common r5532 - trunk/common

[Andreas Dedner]

The problem of fmatrix being a part of dune-common and heavily
used in dune-grid and at the same time being an interface class of
dune-istl is an unfortunate difficulty;
but asking people forced to use fmatrix
(due to the dune-grid interface) to port a small addition to
fmatrix to the dune-istl matricies
(which we hardly use and do not know anything about),
is asking a bit much in my opinion. FMatrix is used in dune-grid not as
an interface class but as the fixed matrix implementation!
And by the way the documentation does not state that this is an
interface class - and an interface class should not contain the
implementation...

If fmatrix has a method mv and umv
and a method umtv then anybody would expect it to have a method
mtv, would you not agree? That is the only thing we added.

If you think that using a work around like Roberts
FMatrixHelp::multAssignTransposed (which does exactly the mtv operation
is the better approach then we can discuss this...

Andreas



Markus Blatt wrote:
> Hi,
> 
> despite living in dune-common, the interface of fmatrix belongs to
> ISTL (at least the one for matrix-vector operations=. If you really
> need this method, you (or some volunteer) should also implement it in all
> ISTL matrices to avoid future surprises. 
> 
> BTW: I am always suprised how fast my fellow developers are in adding
> and implementing interface changes to core modules besides dune-grid.
>  
> Regards,
> 
> Markus
> 
> On Fri, May 29, 2009 at 10:14:02AM +0200, mnolte at dune-project.org wrote:
>> Author: mnolte
>> Date: 2009-05-29 10:14:02 +0200 (Fri, 29 May 2009)
>> New Revision: 5532
>>
>> Modified:
>>    trunk/common/fmatrix.hh
>> Log:
>> add missing method mtv (mv and umtv exist, so mtv should exist, too)
>>
>>
>> Modified: trunk/common/fmatrix.hh
>> ===================================================================
>> --- trunk/common/fmatrix.hh	2009-05-29 08:12:40 UTC (rev 5531)
>> +++ trunk/common/fmatrix.hh	2009-05-29 08:14:02 UTC (rev 5532)
>> @@ -294,13 +294,32 @@
>>        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 i=0; i<n; ++i)
>> +      {
>> +        y[i] = 0;
>> +        for (size_type j=0; j<m; j++)
>> +          y[i] += (*this)[i][j] * x[j];
>> +      }
>> +    }
>> +
>> +    //! y = A^T x
>> +    template< class X, class Y >
>> +    void mtv ( const X &x, Y &y ) const
>>      {
>> -      y[i] = 0;
>> -      for (size_type j=0; j<m; j++)
>> -        y[i] += (*this)[i][j] * x[j];
>> +#ifdef DUNE_FMatrix_WITH_CHECKING
>> +      assert( &x != &y );
>> +      if( x.N() != N() )
>> +        DUNE_THROW( FMatrixError, "Index out of range." );
>> +      if( y.N() != M() )
>> +        DUNE_THROW( FMatrixError, "Index out of range." );
>> +#endif
>> +      for( size_type i = 0; i < m; ++i )
>> +      {
>> +        y[ i ] = 0;
>> +        for( size_type j = 0; j < n; ++j )
>> +          y[ i ] += (*this)[ j ][ i ] * x[ j ];
>> +      }
>>      }
>> -    }
>>  
>>      //! y += A x
>>      template<class X, class Y>
>>
>>
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>>
> 
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