dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, Jan 22, 2008 at 11:09:27AM +0100, Anne Voigt wrote:
> 
> Thank you. I now try to write my own Tensor by deriving from the
> GenericTensor class. Could you write me some information about the interface? 
> Especially what the parameters of the function
> GenericTensor::get(..) and GenericTensor::set(..) are? It is not clear
> for me and I cannot find a documentation about it. 
> 
> Regards,
> Anne

  virtual void set(const real* block,
                   const uint* num_rows,
                   const uint* const * rows) = 0;

block is an array with values to be set

num_rows is an array of length rank()

num_rows[i] is the number of "rows" to be set for axis i

rows[i] is an array with the "rows" to be set for axis i

the length of the array block is num_rows[0]*num_rows[1]*...

For a matrix (rank = 2), the values will be set according to

  for (int i = 0; i < num_rows[0]; ++i)
    for (int j = 0; j < num_rows[1]; ++j)
      A[rows[i], rows[j]] = block[i*num_rows[1] + j];

For a rank 3 tensor, you have three loops etc.

-- 
Anders



> > > 
> > > Am Montag, den 21.01.2008, 16:40 +0100 schrieb Anders Logg:
> > > > On Sun, Jan 20, 2008 at 11:49:57AM +0100, Anne Voigt wrote:
> > > > > -----Ursprüngliche Nachricht-----
> > > > > Von: Ola Skavhaug [mailto:skavhaug@xxxxxxxxx] 
> > > > > Gesendet: Freitag, 18. Januar 2008 23:53
> > > > > An: Anne Voigt; dolfin-dev@xxxxxxxxxx
> > > > > Betreff: Re: [DOLFIN-dev] assemebling process for a trilinearform
> > > > > 
> > > > > Anders Logg skrev den 18/01-2008 følgende:
> > > > > > On Fri, Jan 18, 2008 at 03:56:46PM +0100, Anne Voigt wrote:
> > > > > > > I just wanted to ask if there is any progress with the assembling
> > > > > > > process of a trilinearform.
> > > > > > > As a little reminder, here is what I wrote in December:
> > > > > > > I have the following problem. I defined a trilinearform with the help of
> > > > > > > FFC. Now I wanted to write the results into a 3D tensor which is
> > > > > > > assembled with the help of assemble.h . What I already did I implemented
> > > > > > > a subclass of GenericTensor called Tensor. But unfortunately I am still
> > > > > > > not able to assemble such a tenor. The reason is
> > > > > > > SparsityPatternBuilder.cpp which is not implemented for problems >2D:
> > > > > > > 
> > > > > > >  void SparsityPatternBuilder::build(SparsityPattern& sparsity_pattern,
> > > > > > >  Mesh& mesh,
> > > > > > >                     UFC& ufc)
> > > > > > >  {
> > > > > > >    if (ufc.form.rank() == 0)
> > > > > > >      scalarBuild(sparsity_pattern);
> > > > > > >     else if (ufc.form.rank() == 1)
> > > > > > >      vectorBuild(sparsity_pattern, ufc);
> > > > > > >    else if (ufc.form.rank() == 2)
> > > > > > >     matrixBuild(sparsity_pattern, mesh, ufc);
> > > > > > >    else
> > > > > > >      error("Cannot compute sparsity patterm for size > 2.");
> > > > > > >  }
> > > > > > >  
> > > > > > > I know that you all are very busy that's why I would be already pleased
> > > > > > > if you would be able to tell how much longer I may have to wait?!
> > > > > > > 
> > > > > > > Thanks for your help
> > > > > > > Anne
> > > > > > > 
> > > > > > > _______________________________________________
> > > > > > > DOLFIN-dev mailing list
> > > > > > > DOLFIN-dev@xxxxxxxxxx
> > > > > > > http://www.fenics.org/mailman/listinfo/dolfin-dev
> > > > > > 
> > > > > > We're working on this. The hangup right now is to solve a problem
> > > > > > related to circular dependencies between matrix classes and matrix
> > > > > > factories (in particular for uBLAS where things are templated).
> > > > > > 
> > > > > > We may have found a solution today (in particular Martin who has a
> > > > > > black belt in templates). Ola, did it work?
> > > > > 
> > > > > Sure, it did. I have to compile DOLFIN using PETSc for all the part to
> > > > > fit together. I'll probably commit early next week.
> > > > > 
> > > > > Ola
> > > > >  
> > > > > 
> > > > > Great news!!! Thanks to all of you. Now I can go ahead with my final
> > > > > thesis!!! :-)
> > > > > 
> > > > > Anne
> > > > 
> > > > ok, it might be fixed now. Try and see if you can make it work.
> > > > 
> > > > What we've done (mostly Ola and Martin) is that we have added a method
> > > > factory() to the interfaces. These should for each backend return a
> > > > factory that knows how to create vectors and matrices, and sparsity
> > > > patterns for that backend.
> > > > 
> > > > What you need to do to assemble into your own tensor is to implement
> > > > your own tensor class (subclass of GenericTensor), your own factory
> > > > (subclass of LinearAlgebraFactory) and your own sparsity pattern
> > > > (subclass of GenericSparsityPattern).
> > > > 
> > > > The assembler will ask your tensor to return a factory and then it
> > > > will ask that factory to create a sparsity pattern. Before assembling
> > > > into your tensor, it will iterate over the elements and let you build
> > > > the sparsity pattern. Depending on how you have implemented your
> > > > tensor class, you may or may not want to actually build the sparsity
> > > > pattern.
> > > > 
> > > > See if it works.
> > > > 
> > > 
> > 
> 
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