[Trilinos-Users] Calculation of eigenvalues of an Epetra_CrsMatrix fails when using Ifpack

[Roland Richter]

Hei,

I am trying to calculate the eigenvalues of a given matrix (jacobian of
a system) by using the attached code (with system_matrix containing the
jacobian). Now two questions arose:

-> When using the preconditioner Ifpack (as suggested in an example),
the solver never converges. Without the preconditioner the solver
converges, but slowly (for a simple poisson equation)
-> When calculating the eigenvalues for the poisson equation, the
largest eigenvalues are negative, but for the heat equation the largest
eigenvalues are positive, indicating an unstable system. Did I do
something wrong here?

Thanks,

regards,

Roland

-------------- next part --------------
A non-text attachment was scrubbed...
Name: anasazi_code.cpp
Type: text/x-c++src
Size: 4961 bytes
Desc: not available
URL: <https://trilinos.org/pipermail/trilinos-users/attachments/20191003/35d994e8/attachment.bin>