On 11/01/2011 04:31 PM, Roy Stogner wrote:
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?
Roy, I've attached a version of ex17 with dirichlet boundary conditions,
if you're interested in testing that out in complex mode. (Note: it uses
CondensedEigenSystem, which I use in rbOOmit in order to compute
eigenvalues without introducing spurious behavior due to the presence of
Dirichlet dofs)
David
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