dolfin team mailing list archive

["Martin Sandve Alnæs" <martinal@xxxxxxxxx>]

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/.
>
> --
> Anders

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.

--
Martin