dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Wed, Dec 12, 2007 at 09:03:20AM +0100, Martin Sandve Alnæs wrote:
> 2007/12/11, Anders Logg <logg@xxxxxxxxx>:
> > On Tue, Dec 11, 2007 at 02:58:58PM +0000, Garth N. Wells wrote:
> > >
> > >
> > > Ola Skavhaug wrote:
> > > > Hi,
> > > >
> > > > I'm trying to assemble dolfin/FFC forms into a user given matrix format
> > > > CRSNew, which inherits GenericTensor as it should. However, the assemble.py in
> > > > src/python in dolfin does not allow this.
> > > >
> > >
> > > assembly.py has rather limited functionality compared to
> > > dolfin::assemble. Does assembly into CRSNew using c++ work?.
> >
> > Yes, assemble() in PyDOLFIN currently assumes that you give it an FFC
> > form and a Mesh. It then calls the JIT compiler on the form and then
> > calls the wrapped C++ assembler on the generated UFC code.
> >
> > Does it work if you use cpp_assemble() instead of assemble()?
> >
> > We should try and extend assemble() in Python so it can recognize
> > various combinations of input arguments (an FFC form or a UFC etc).
> >
> > The assemble() function is just a few lines of code and it's defined
> > in assemble.py in src/pydolfin/.
> >
> 
> Have you tried using the Assembler and not the function assemble(..)?
> 
> Earlier this autumn this worked for me with a ufc form from syfi (but
> of course not with the new CRSNew matrix):
> 
> 
> from dolfin import *
> 
> mesh = UnitSquare(3, 3)
> asm  = Assembler(mesh)
> 
> coefficients = ArrayFunctionPtr()
> cell_domains           = None
> exterior_facet_domains = None
> interior_facet_domains = None
> reset_tensor = True
> 
> A = Matrix() #A = CRSNew()
> print type(A)
> print isinstance(A, dolfin.GenericTensor)
> asm.assemble(A, form, coefficients, cell_domains,
> exterior_facet_domains, interior_facet_domains, reset_tensor)
> A.disp()
> 
> 
> Note that the default arguments for domains etc didn't work then, this
> should be possible to achieve. Also, a typemap to handle a python
> sequence of coefficients instead of the ArrayFunctionPtr would make it
> much better. I have some typemaps in my pycc Assembler which checks
> all items in a list for type and allows f.ex.
> 
> A = asm.assemble_matrix(form, [1.23, (1.0, 2.0, 3.0), my_function,
> my_numpy_array])
> 
> It wraps constants and constant tuples into my equivalent of Function
> (for those who know pycc, not the regular pycc::ScalarFunction etc).
> For a GenericVector (again my equivalent of the dolfin one) it just
> checks the length and assumes everything is fine.
> 
> Anders, I can show you my typemap code, I think you can reuse much of
> it for this.

Yes, that would be nice. But I haven't checked Ola's code yet, maybe
he has already fixed this? Sending Python lists instead of
ArrayFunctionPtr (which should not really be exposed in the Python
interface) would be very nice.

-- 
Anders