dolfin team mailing list archive

["Andy Ray Terrel" <aterrel@xxxxxxxxxxxx>]

On Thu, Sep 18, 2008 at 8:21 AM, Johan Hake <hake@xxxxxxxxx> wrote:
> On Thursday 18 September 2008 03:21:23 Ostien, Jakob T wrote:
>> Hi,
>>
>> I got myself confused with the down_cast functionality.  Say I assemble
>> three bilinear forms into Matrix A, B, and C, and then consider the
>> expression:
>>
>> K  = A - A (B^-1) C
>>
>> (which I actually want to do, go figure).  I like the uBLAS backend so I
>> would like to try
>>
>> A.mat() - ublas::prod( A.mat(), ublas::prod( B.invert(), C.mat() ) )
>>
>> But when I try and down_cast from dolfin::Matrix to uBLASMatrix with
>>
>> uBLASDenseMatrix AA = A.down_cast<uBLASDenseMatrix>();
>
> Hello!
>
> Did you mean:
>
>  dolfin::uBLASMatrix AA = A.down_cast<dolfin::uBLASMatrix>()
>
> Otherwise you should try that! :)
>
> Johan
>
>> I get a message that down_cast doesn't live in the Matrix class (even
>> though its in the GenericTensor class).
>>
>> So I ask, what is the intended usage to get a uBLASMatrix from a Matrix?
>>
>> Thanks,
>> Jake
>>
>>
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>
>
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I tried:

  Matrix A;
  uBLASMatrix<ublas_sparse_matrix> mat;
  mat = A.down_cast< uBLASMatrix<ublas_sparse_matrix> >();


And it worked but once I changed sparse to dense the dynamic_cast
died.  My guess would be because the ublas matrix starts off its life
as a sparse matrix ublas doesn't allow some change in the format.  You
might try just starting out with the matrix type you want first.

-- Andy