[Getfem-users] assembling Matrix

[maruetti]

Hi,

I want to solve the following problem using the getFem++ Matlab interface:

Mr'' + Kr' = G exp(iwt)

using r = g exp(iwt)

I get

(-w^2 M + K)g exp(iwt) = G exp(iwt)

=> (K-w^2M)^-1 G = g

where K is the Stiffness and M the Mass Matrix of the problem. I want
to solve the problem for a plate with fixed sides.

My problem is that I don't know how to assemble the Matrices and to
introduce the boundary conditions. I tried the following thing:


%% Mass Matrix
noMeshElements = gf_mesh_get(m,'nbcvs');
massMatrix = gf_asm('mass matrix', mfu);

%% Stiffness Matrix
lambdaF = lambda*ones(noMeshElements, 1);
muF = mu*ones(noMeshElements, 1);
stiffnessMatrix = gf_asm('linear elasticity', mfu, mfd, lambdaF, muF);

%% Force on each element of the Plate
FVolume = [0,0,G]';
volumeForceMatrix = repmat(FVolume, 1, noMeshElements);
forceInput = gf_asm('volumic source', mfu, mfd, volumeForceMatrix);


how to set 'dirichlet' boundary condition?

Thank you

         Mario