dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

Gerd Wachsmuth skrev 2010-10-21 12.58:
> On Wed, 20 Oct 2010, Anders Logg wrote:
>> Marie Rognes skrev 2010-10-14 12.28:
>>> On 14. okt. 2010 11:13, Gerd Wachsmuth wrote:
>>>> This works fine in 2D. But in 3D, extrapolation is not implemented.
>>>>
>>>>
>>>
>>> Ah.
>>>
>>
>> The problem is that this functionality is missing in CGAL so we have to
>> implement it ourselves and no one has done that yet.
>>
>
> In my opinion the problem is that Dolfin want to evaluate the function at
> points which does not belong to the integration domain - or at points
> lying to close at the boundary.
>
> In my example the function w is defined only on a subdomain. Hence there
> should be no error if this function is integrated over this subdomain.
> By extrapolating this bug is only covered up.

Have you checked which point is thought to be outside of the domain? 
Perhaps it's a small round-off error that causes the problem?

-- 
Anders

-- 
Assembling over subdomain fails
https://bugs.launchpad.net/bugs/660334
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Status in DOLFIN: New

Bug description:
Following setup:

I have a mesh (with FunctionSpace V) and a submesh (with FunctionSpace W). Assembling a linear form on V over this subdomain involving a coefficient from W will fail.

I think the problem is that Dolfin would like to evaluate the function from W at the boundary of the subdomain. Maybe due to rounding errors this point lies outside the subdomain and the evaluation fails.

It does not happen, if W is a CG or DG space.