dolfin team mailing list archive

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

On Wed, Dec 17, 2008 at 11:32 PM, Martin Sandve Alnæs
<martinal@xxxxxxxxx> wrote:
> On Wed, Dec 17, 2008 at 6:35 PM, Anders Logg <logg@xxxxxxxxx> wrote:
>> On Wed, Dec 17, 2008 at 06:08:14PM +0100, Johan Hake wrote:
>>> On Wednesday 17 December 2008 17:54:23 Martin Sandve Alnæs wrote:
>>> > On Wed, Dec 17, 2008 at 5:42 PM, Johan Hake <hake@xxxxxxxxx> wrote:
>>> > > On Wednesday 17 December 2008 16:34:16 Anders Logg wrote:
>>> > >> On Wed, Dec 17, 2008 at 01:58:35PM +0100, Martin Sandve Alnæs wrote:
>>> > >> > Using latest hg versions of everything, I'm trying to plot a Function
>>> > >> > from C++ based on a SFC-generated function space and I get:
>>> > >> >
>>> > >> > Failed to read DOLFIN mesh or function XML file for plotting:
>>> > >> >   *** Error: Unable to find dof map in library:
>>> > >> > "FiniteElement('Lagrange', 'triangle', 1)".
>>> > >> > Unable to plot (DOLFIN Python module or Viper plotter not available).
>>> > >> >
>>> > >> > Can I suggest using Function::interpolate to make a .vtu file to plot
>>> > >> > instead of relying on a form compiler specific precompiled element
>>> > >> > library?
>>> > >> >
>>> > >> > Martin
>>> > >>
>>> > >> Sounds like a good idea. We now generate Python script that loads the
>>> > >> Function (or Mesh) from file and then calls Viper from Python.
>>> > >>
>>> > >> Does Viper support direct plotting of .vtu files? In that case, we
>>> > >> would not need to call Python from C++. We could generate a .vtu file
>>> > >> and then call Viper with that file (using system()).
>>> > >>
>>> > >> I don't have time to fix this now, so either find someone to fix it or
>>> > >> put it on the TODO list.
>>> >
>>> > What is in use, the text file or bugzilla?
>>> >
>>> > > We could also plot a cpp.Function instead of a dolfin.Function. That fix
>>> > > would not be so extensive. I had a brief look at it but couldn't find out
>>> > > where
>>> > >
>>> > >   Function(filename)
>>> > >
>>> > > was called.
>>> > >
>>> > > Johan
>>> >
>>> > I also want to write a Function to file in C++.
>>> > What are the requirements on the FunctionSpace
>>> > to be able to do that?
>>>
>>> I think that the only requirement is that the element should be defined in
>>>
>>>   dolfin/elements/elements.py
>>even
>> That should only be required for reading.
>
> That's probably what I want.
>
> The strings there use "triangle" instead of 'triangle' which is what
> repr("triangle") returns. This doesn't match with the UFL
> implementation of repr(element), and this is where my current attempt
> failed.
>
> Even when this is fixed, one way or the other, this element library is
> ffc specific. I don't know exactly how compatible the dofmaps from ffc
> and sfc are, and I'm not sure how to fix this...
>
> Martin

Just a small thought... Is it possible today to provide an existing
FunctionSpace to a Function that is being read from file?
Something like (I know this constructor is not there):

    Function f(V, filename);

If it's not possible in any other way, that should be added anyway
to allow reuse of function spaces across functions. In this case,
I wouldn't need to worry about the element library since I provide
my own FunctionSpace.

Martin