Python<->C cross-language interoperability

[Barry Smith]

   I have run the example.

   BTW: run with -snes_monitor the nonlinear convergence is terribly  
slow.

   BTW: I have added a --download-numpy and --download-petsc4py to  
petsc-dev. Preliminary version
uses the SVN versions. Eventually I'd like it to auto-select the  
correct version.

    Barry

On Nov 23, 2007, at 2:38 PM, Lisandro Dalcin wrote:

> On 11/23/07, Matthew Knepley <knepley at gmail.com> wrote:
>> Yes, we should definitely do this. I think I already have the  
>> support for
>> linking to the Python library somewhere.
>>
>>> Perhaps I will also ask in the near future for adding two 'slots' in
>>> the base PetscObject structure for better supporting petsc4py.
>>
>> Yes, this is fine too. We should try and do it before the next  
>> release
>> since it will be a major release.
>
> Nice, then I'll try to add the needed changes in petsc-dev, and I'll
> will surely need your help for adding support in configure system.
>
>>> If any of you want to take a look, I have a trivial C SNES example,
>>
>> Cool, where is it?
>
> Well, all this is in petsc4py SVN repo, the specific example for SNES
> is at this location:
>
> http://petsc4py.googlecode.com/svn/trunk/petsc/lib/ext/petsc/src/snes/impls/python/
>
> The C example is 'ex1.c' (note the line calling Py_Initialize() ), the
> equivalent Python example is 'ex1.py'. Both examples calls the methods
> of class 'MyNewton' (implemented in file 'mysolver.py').
>
> The actual SNESPYTHON type is implemented in file 'python.c', but that
> type is actually available through petsc4py, and automatically
> registered at import time.
>
> To run the example, you have to build petsc4py SVN using petsc-2.3.3
> or petsc-dev (use shared libs), and install petsc4py somewere (and put
> that location on PYTHONPATH). After that, build 'ex1.c' (the
> 'makefile' is using the old bmake paths, fix for the petsc-dev case)
> and run it like the following;
>
> $ make ex1
> $ ./ex1 -snes_type python -trace
>
> Your will see in your terminal (because of -trace option, look at
> mysolver.py at MyNewton.setFromOptions() methods) a lot of ouput
> showing the methods and aguments passed during the complete nonlinear
> solve.
>
> Ask me if you have trouble with something.
>
> I'll wait for your comments. Please note that all this is very
> preliminar and was develeped in a couple of days, there is room for a
> lot of improvement.
>
>
> -- 
> Lisandro Dalcín
> ---------------
> Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
> Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
> Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
> PTLC - Güemes 3450, (3000) Santa Fe, Argentina
> Tel/Fax: +54-(0)342-451.1594
>