Johan Hake wrote:
> On Wednesday 19 August 2009 18:50:13 Garth N. Wells wrote:
>> Johan Hake wrote:
>>> On Wednesday 19 August 2009 17:29:52 Garth N. Wells wrote:
>>>> What's going on behind the scene when I copy one vector to another in
>>>> PyDOLFIN using
>>>>
>>>> u0.vector()[:] = u.vector()[:]
>>> When I add:
>>>
>>> u2 = Function(V)
>>> u2.vector()[:] = u.vector()[:]
>>>
>>> # Plot solution
>>> plot(u2)
>>>
>>> In a the Poisson demo it works fine.
>> In parallel?
>
> Yupp!
>
>>> This type of slice only uses the assignment operator.
>> The GenericVector assignment operator?
>
> Yes. This is done in __setslice__/__getslice__ in the extended python class.
>
I don't see then why the we end up inside
_compare_vector_with_vector
for the Cahn-Hilliard demo when running in parallel?
>> I delved into the problem and the program ends up in the function
>> _compare_vector_with_vector from dolfin_la_get_set_items.i. It uses
>> GenericVector::get and GenericVector::set. These need to be used with
>> caution in parallel.
>
> Yes, when other type of slices are used we need to find a way to do that in
> parallel. I have just started digging in the parallel code, and need to look
> into all the changes to get familiar with it before I try to solve this.
>
This shouldn't be too hard.
set(const double* block, uint m, const uint* rows)
works in parallel but
get(double* block, uint m, const uint* rows)
doesn't yet (not too hard to fix though). The really evil functions are
set(const double*)
and
get(double*)
Garth
> The best solution would be to have a full fledge VectotView in place ;)
>
> Johan
>
>> Garth
>>
>> Other slices might not
>>
>>> work. Have not checked.
>>>
>>> Johan
>>>
>>>> ? The issue is that it doesn't work in parallel.
>>>>
>>>> Garth
>>>> _______________________________________________
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