Hi Lawrence, ok, so if I apply the BCs to u before the multiplication and to v after the multiplication I would expect the result to be the same in both versions, but it doesn’t look like it. Thanks, Eike
On 27 Apr 2015, at 12:19, Lawrence Mitchell <lawrence.mitchell@imperial.ac.uk> wrote:
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On 27/04/15 12:04, Eike Mueller wrote:
Dear firedrakers,
Assume I have assembled a UFL form in the HDiv space:
form_uu = [a UFL form] mat_uu = assemble(form_uu,bcs=bcs)
This assembles an operator with bcs applied, useable in a linear solver. The rows /and/ columns corresponding to the BC nodes are the identity.
then shouldn’t the following two experssions fo exactly the same thing?
version A: with v.dat.vec as y: with u.dat.vec_ro as x: mat_uu.M.handle.mult(x,y)
So this computes I_{Gamma} + A_{Omega \ Gamma}, i.e. on the boundary nodes y is x elsewhere it's Ax.
version B: v = self._mutilde._form_action(u)
This computes the action of A on u /without/ boundary conditions. What are you expecting to see?, Ax on the non-boundary condition nodes, bc-value on the boundary values?
as fas as I can tell, only version B gives the correct result in my case.
Lawrence -----BEGIN PGP SIGNATURE----- Version: GnuPG v1
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