[firedrake] Boundary conditions

[Cotter, Colin J]

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<mailto: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

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