dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Wed, Dec 03, 2008 at 07:01:04PM +0100, Johan Hake wrote:
> On Wednesday 03 December 2008 18:04:54 Anders Logg wrote:
> > On Wed, Dec 03, 2008 at 05:28:21PM +0100, Johan Hake wrote:
> > > On Wednesday 03 December 2008 15:43:43 Anders Logg wrote:
> > > > On Wed, Dec 03, 2008 at 03:08:32PM +0100, Anders Logg wrote:
> > > > > On Wed, Dec 03, 2008 at 02:57:09PM +0100, Johan Hake wrote:
> > > > > > On Wednesday 03 December 2008 13:54:47 DOLFIN wrote:
> > > > > > > One or more new changesets pushed to the primary dolfin
> > > > > > > repository. A short summary of the last three changesets is
> > > > > > > included below.
> > > > > > >
> > > > > > > changeset:   5221:0e4bbb39f032405bcc4abfab501af49f6beb7b0b
> > > > > > > tag:         tip
> > > > > > > user:        Anders Logg <logg@xxxxxxxxx>
> > > > > > > date:        Wed Dec 03 13:54:05 2008 +0100
> > > > > > > files:       demo/pde/poisson/python/demo.py
> > > > > > > dolfin/swig/directors.i dolfin/swig/dolfin_mesh_pre.i
> > > > > > > description:
> > > > > > > Typemap fixes for SubDomain::inside(), seems to work now.
> > > > > >
> > > > > > Nice work!
> > > > > >
> > > > > > I suppose you are aware that the director typemap only kicks in for
> > > > > > Function and SubDomain as these are the only director classes that
> > > > > > includes a double* x, in one of their signatures. If other director
> > > > > > classes in a possible future implements that signature, will
> > > > > > trigger the typemap and that class need to implement
> > > > > > geometric_dimension(). It is a nice way to solve the dimension
> > > > > > problem of the numpy array, we just need to be aware of possible
> > > > > > fragile side effects.
> > > > >
> > > > > Yes, that was the main point, to have a common typemap for both.
> > > > >
> > > > > > I introduced the class specific typemap with Function in mind,
> > > > > > which you now have generalized to work for any "double* x" used in
> > > > > > directors. We could hypotethize that this could be done for more
> > > > > > "double*" typemaps too.
> > > > > >
> > > > > > Most of them are now implemented as a very fragile and greedy numpy
> > > > > > typemap that kicks in every where a "double *" is expected. This
> > > > > > typemap depends on the user passing the right dimension on the
> > > > > > array to the function. This is inherited from the cpp interface
> > > > > > where you have natural relationship to size of arrays. But I think
> > > > > > that it does not scale to python.
> > > > > >
> > > > > > Optimally we should use a dimension check for each double * typemap
> > > > > > that expect a numpy array, where the size of the numpy array is
> > > > > > defined from the contex the type map is applied in. E.g. a type map
> > > > > > for the Vector.set(), could check the size of the array agains the
> > > > > > size of the Vector. The problem with this is to make a specific
> > > > > > typemap that we know only kicks in for a particular class.
> > > > >
> > > > > I know too little SWIG to have an opinion on this.
> > > > >
> > > > > > To facilitate this we could change the parameter name in the
> > > > > > Vector.set(double* value) to Vector.set(double* vecvalue) and to
> > > > > > add the typemap:
> > > > > > (pseudo code)
> > > > > > %typemap(in) double* vecvalues {
> > > > > >   {
> > > > > >     Check input is numpy array.
> > > > > >     // This is safe as long as only Vectors implement "double*
> > > > > > vecvalues" Check dimension of numpy array agains self->size()
> > > > > >     Assign the input statement.
> > > > > >   }
> > > > > > }
> > > > >
> > > > > But I'd like to avoid this (choosing special names for the arguments
> > > > > in C++ just to please SWIG).
> > > > >
> > > > > > We should also %ignore alot of low level cpp only functions from
> > > > > > the especially the la interface. Removing alot of the fragile
> > > > > > double* typemaps that now kicks in everywhere.
> > > > >
> > > > > Agree!
> > > > >
> > > > > I'm about to get started on renaming dolfin.dolfin --> dolfin.cpp.
> > > > > Let's see how it goes.
> > > >
> > > > Didn't go well. I don't know enough about the build system to make
> > > > this work.
> > > >
> > > > Can you take a look?
> > >
> > > Yes. I do it to night.
> >
> > ok, nice.
> >
> > I'll probably try to push some changes before then.
> 
> I have done quite abit already. You deside if you want to push.

Nothing on the Python stuff so just go ahead. I'll let you push before
I touch it again, probably not until tomorrow.

I'm thinking of adding a Form class (in form.py) which will replace
(and reuse) get_dolfin_form in assemble.py. It should be a class that
can take whatever arguments thrown at it (FFC form, or UFC form) and
instantiate a cpp.Form object.

Then we can reuse it in both assemble() and LinearPDE. Hopefully, we
may then remove the special implementation of LinearPDE in pde.py and
just reuse C++ implementation: first create Form objects, then send
those to cpp.LinearPDE, then return the solution in solve().

If you're hacking on assemble.py, feel free to reshape get_dolfin_form
into a Form class (in form.py). Otherwise, I'll take a look once
you're done.

-- 
Anders

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