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Extract Inner-Product-Matrices to Matlab?

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Hello to all!

Does anyone know, how to access the inner product matrices in Comsol 4.2a in Matlab?

I would like to compute different norms of a solution u.
The Euclidian norm simply is: u' * u
If I want the L2 norm, I have to calculate u' * L2 * u
or for the H1 norm: u' * H1 * u
with the inner-product-matrices L2 or H1.

But how do I extract these inner-product-matrices L2 or H1 from Comsol? I think the L2-inner-product-matrix should be:
L2 = mphmatrix(model,'sol1','Out', 'D')
Right?

But how can I get the H1-inner-product- matrix?

Thank you very much
Oli

1 Reply Last Post 25.09.2012, 05:08 GMT-4
Nils Malm COMSOL Employee

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Posted: 1 decade ago 25.09.2012, 05:08 GMT-4
Hi Oli,
The H1 inner product matrix is essentially the same as the "K" matrix for a Coefficient form PDE with c=a=1, remaining coefficients equal to zero, assembled using the mphmatrix command.

best regards
Nils Malm
COMSOL AB
Hi Oli, The H1 inner product matrix is essentially the same as the "K" matrix for a Coefficient form PDE with c=a=1, remaining coefficients equal to zero, assembled using the mphmatrix command. best regards Nils Malm COMSOL AB

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