[firedrake] Boundary conditions

[David Ham]

Actually it's even simpler:

mymatrix = assemble(myform, bcs=bcs)

mymatrix.M.values

As soon as you look at M, the evaluation is forced. It's all very
Schrödinger.


On 2 February 2014 10:30, David Ham <David.Ham at imperial.ac.uk> wrote:

>
> mymatrix = assemble(myform, bcs=bcs)
>
> mymatrix.assemble() # Force the delayed assembly.
>
> mymatrix.M.values # Numpy array.
>
>
>
> On 2 February 2014 09:04, Cotter, Colin J <colin.cotter at imperial.ac.uk>wrote:
>
>>  OK, next question is whether I can output a numpy matrix for a bilinear
>> form assembled with boundary conditions, i.e. whether I can get the reduced
>> matrix with the boundary rows and columns removed?
>>
>> I can see that the bcs are postponed until the solve, so if this exists
>> it would just be a utility for testing. If it doesn't I can remove them
>> myself.
>>
>> --cjc
>>  ------------------------------
>> *From:* firedrake-bounces at imperial.ac.uk [
>> firedrake-bounces at imperial.ac.uk] on behalf of Cotter, Colin J [
>> colin.cotter at imperial.ac.uk]
>> *Sent:* 02 February 2014 08:54
>>
>> *To:* firedrake
>> *Subject:* Re: [firedrake] Boundary conditions
>>
>>   Ah good, works, thanks.
>>
>> --cjc
>>  ------------------------------
>> *From:* firedrake-bounces at imperial.ac.uk [
>> firedrake-bounces at imperial.ac.uk] on behalf of David Ham [
>> David.Ham at imperial.ac.uk]
>> *Sent:* 01 February 2014 22:12
>> *To:* firedrake
>> *Subject:* Re: [firedrake] Boundary conditions
>>
>>  Standard GMSH problem: if you have a physical line you also need a
>> physical surface or GMSH will drop all the interior elements from the
>> output.
>>
>> On Saturday, February 1, 2014, Cotter, Colin J <
>> colin.cotter at imperial.ac.uk> wrote:
>>
>>>  Dear Firedrakers,
>>>   I decided to create another set of cohomology tests, this time with
>>> Dirichlet boundary conditions, since there is a nice result relating the
>>> kernels of the operators with and without Dirichlet boundary conditions
>>> (for the maths-curious, it's Poincare duality).
>>>
>>>   However, I can't get the boundary tags into Firedrake from gmsh. If I
>>> attempt to tag the boundary using "Physical Line" in gmsh (see bottom of
>>> this email for the .geo file), the line
>>> >>mesh = Mesh("annulus.msh")
>>> produces:
>>> *** ERROR ***
>>> Error message: Unsupported mixture of face/element types
>>>
>>> Removing the physical line makes the error message go away, so there is
>>> something wrong with that line.
>>>
>>> What have I done wrong?
>>>
>>> all the best
>>> --Colin
>>>
>>> Point(1) = {0, 0, 0, 1.0};
>>> Point(2) = {1, 0, 0, 1.0};
>>> Point(3) = {1, 1, 0, 1.0};
>>> Point(4) = {0, 1, 0, 1.0};
>>> Point(5) = {0.3333333333333, 0.3333333333333, 0, 1.0};
>>> Point(6) = {0.66666666666666, 0.3333333333333, 0, 1.0};
>>> Point(7) = {0.66666666666666, 0.66666666666666, 0, 1.0};
>>> Point(8) = {0.3333333333333, 0.66666666666666, 0, 1.0};
>>> Line(1) = {1, 2};
>>> Line(2) = {2, 3};
>>> Line(3) = {3, 4};
>>> Line(4) = {4, 1};
>>> Line(5) = {5, 6};
>>> Line(6) = {6, 7};
>>> Line(7) = {7, 8};
>>> Line(8) = {8, 5};
>>> Line Loop(1) = {1, 2, 3, 4};
>>> Line Loop(2) = {5, 6, 7, 8};
>>> Plane Surface(1) = {1,2};
>>> Physical Line(9) = {2, 3, 4, 1, 6, 7, 8, 5};
>>>
>>>
>>
>> --
>> Dr David Ham
>> Departments of Mathematics and Computing
>> Imperial College London
>>
>> http://www.imperial.ac.uk/people/david.ham
>>
>>
>
>
> --
> Dr David Ham
> Departments of Mathematics and Computing
> Imperial College London
>
> http://www.imperial.ac.uk/people/david.ham
>



-- 
Dr David Ham
Departments of Mathematics and Computing
Imperial College London

http://www.imperial.ac.uk/people/david.ham
-------------- next part --------------
HTML attachment scrubbed and removed