Toon Weyens <[email protected]> writes: > Yes, you are probably right: My code is not yet bug free (by all means!). > However, I have been working very hard on it and I will see if I find > something. B should not ever be really singular! > > I do, however, still have some questions: > > - Does slepc detect whether my matrix is tridiagonal and does it apply a > direct method to solve it? Or do you talk about it in general: that it > would be better for me to use a direct method that is not part of slepc?
The direct method is just a default. For a tridiagonal matrix, there is no fill, so direct methods have great complexity. For other problems (multi-dimensional, etc.) the direct solver has fill and becomes asymptotically suboptimal. > - How do I make use of the information that both A and B have the same > non-zero structure? Is there an easy way? I don't think it could make any difference for your scenario. > - What is the call "MatSetOption(mat,MAT_HERMITIAN,PETSC_TRUE,ierr)" do? Is > it important? It does not seem to influence anything... In some circumstances, it would cause a method to default to Lanczos instead of Arnoldi, or Cholesky instead of LU.
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