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Question regarding assembled matrices

Posted 11 oct. 2011, 20:05 UTC−4 Version 3.5a 0 Replies

Giorgos Kourakos
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Hi everyone

I have question about the assemble command
[K,L,M,N] = assemble(fem);
which actually return the matrices of the linear system being solved.
If I have got it right the M corresponds to the values of dirichlet BC.
What I want to do is to change iteratively the values of M i.e. change my constant BC and resolve using
fem.sol = femstatic('In',{'K' K 'L' L 'M' M 'N' N});
without assembling the matrices again as the problem is rather large 1e6 dof.

My issue now is that the format of M is nx1 where n are the number of nodes with the imposed BC.

After I solve the system fem.sol.u has of course the size of ndof x 1.
How can I identify the n elements of fem.sol.u which are actually constant?

Thank you in advance

Giorgos

0 Replies Last Post 11 oct. 2011, 20:05 UTC−4
COMSOL Moderator

Hello Giorgos Kourakos

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