[petsc-dev] Question About Petsc ILU

[Dave Nystrom]

I have recently added the capability to have a separate preconditioning
matrix in the petsc interface for the code I am working with.  I have two
types of preconditioning matrices that I have questions about.  One is
tridiagonal and the other is 7 diagonals.  In both cases, the the diagonals
are all lexically adjacent.  Or phrased differently, the tridiagonal matrix
has a bandwidth of 3 and the 7 diagonal matrix has a bandwidth of 7 and so
they are compact or dense band systems.

I was wondering what petsc ilu will do for preconditioning matrices like
these.  Will it produce an exact lu factorization or a nearly exact
factorization?  I'm interested in the answer to this question because I am
thinking I might be able to run this preconditioner on the gpu using the
txpetscgpu package.

Thanks,

Dave