On Tue, 1 Nov 2011, Jed Brown wrote:
> The error "IPNorm: The inner product is not well defined!" is
> usually due to the fact that the B matrix of the eigenproblem is not
> positive (semi) definite. Are you sure your eigenproblem is
> definite?
It's definitely *supposed* to be; this is just the ex17 code that
builds a laplacian stiffness and L2 mass matrix, as you said. I can
even switch from Q_1 quads to P_1 line segments, and as long as I use
at least 3 of them (4 nodes) I still get that IPNorm error. Although,
tweaking the mesh does seem to change the stack trace; the IPNorm
starts coming from different calls to IPOrthogonalize, then from
EPSComputeVectors_Hermitian, as I shrink things.
> In that case, I would be interested in trying these
> matrices to track down the problem.
matrix_A = [Real part:
1.5 -1.5 0 0
-1.5 3 -1.5 0
0 -1.5 3 -1.5
0 0 -1.5 1.5
Imaginary part:
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
];
matrix_B = [Real part:
0.222222 0.111111 0 0
0.111111 0.444444 0.111111 0
0 0.111111 0.444444 0.111111
0 0 0.111111 0.222222
Imaginary part:
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
];
I forgot to set_precision() on that, but you get the idea.
matrix_B is SPD. matrix_A isn't, but that just ought to mean that one
of our eigenvalues is 0, right?
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Roy
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