[petsc-users] ILUTP

[Torquil Macdonald Sørensen]

Hi!

I have a linear problem Ax=b, with complex values, that is solved very well
using the ILUTP and GMRES implementations in GMM++. None of the other
preconditioners available in GMM++ would work (e.g. ILU and ILUT) for this
problem.

Then I tried the same problem using ILU and GMRES in PETSc, with no
success, despite a lot of attempts at adjusting ILU settings. I always end
up with gigantic residual norm values. The same PETSc program works well
when I apply it to a different matrix A.

I'm now suspecting that the ILU options cannot be set so as to obtain ILUTP
behaviour.

What would be the recommended method to access an ILUTP preconditioner from
PETSc?

According to the PETSc website, a preconditioner named ILUDT is available
by using the external package Hypre, but I had to deselect Hypre during the
PETSc build due to my use of complex numbers... So do you guys think that I
should transform everything to a real representation and try Hypre/ILUDT?

Best regards
Torquil Sørensen
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