dolfin team mailing list archive

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

On Wed, Jan 7, 2009 at 3:26 PM, Garth N. Wells <gnw20@xxxxxxxxx> wrote:
>
>
> Martin Sandve Alnæs wrote:
>>
>> On Wed, Jan 7, 2009 at 3:09 PM, Garth N. Wells <gnw20@xxxxxxxxx> wrote:
>>>
>>> Anders Logg wrote:
>>>>
>>>> On Wed, Jan 07, 2009 at 02:49:17PM +0100, Johan Hake wrote:
>>>>>
>>>>> On Wednesday 07 January 2009 14:28:09 Kent Andre wrote:
>>>>>>
>>>>>> It seems to me that the problem is that I have created two different
>>>>>> FunctionSpaces that are actually the same and that the test
>>>>>> in Function is a pointer check.
>>>>>>
>>>>>> One could of course make a better check based on e.g. a signature.
>>>>>> This should be trivial to do. But I will end up with using
>>>>>> a bit more memory than needed. Is this an acceptable solution ?
>>>>>
>>>>> A check for the signature is not enough. Eventually we have to check
>>>>> for the
>>>>> meshes in the two files being the same too.
>>>>
>>>> Maybe we should add a signature() function for meshes also that
>>>> returns some kind of checksum for the mesh?
>>>>
>>> What's wrong with the approach that I presented? Just read the function
>>> and extract from the function the FunctionSpace and the mesh?
>>>
>>> Garth
>>
>> Reading ten functions from file gives ten meshes in memory.
>>
>
> This is another issue. Kent's code was reading in one function only.
>
> I have a dislike for reading and writing functions, mainly because of the
> use of signatures and the presence of pre-compiled finite elements in DOLFIN
> (the latter going against the spirit of automated generation). The most
> general approach would be to allow the construction of a Function with a
> FunctionSpace and a GenericVector. The user has to take some responsibility
> in making sure that the DofMap, Mesh, FiniteElement and GenericVector match.
> From a quick look at the code, the only extra thing that would be needed is
> a Function constructor that accepts a FunctionSpace and a GenericVector.
>
> Garth

Ok.

Since the user has to keep track of the surrounding context anyway,
I'd like to simply do this for restarting simulations etc:

file << u.vector()
file >> u.vector()

Writing vectors seems to work fine with .xml files.

It would also be nice to be able to dump the vector contents to a raw
binary file, which should be faster and reduce the disc space needed.

Martin