[petsc-users] KSPSetDiagonalScale

[Jed Brown]

It just means that both matrix arguments A and B are the same.

What happens if you use this direct solver as a preconditioner?
On May 17, 2012 2:23 PM, "Colin McAuliffe" <cjm2176 at columbia.edu> wrote:

> Hello!
>
> I am solving a coupled multiphysics problem which has several different
> units, which leads to a poorly conditioned jacobian. I am using the
> following ksp options:
>
> -ksp_type preonly -pc_type lu -pc_factor_mat_solver_package umfpack
>
> The results I am getting are not right and I suspect that the conditioning
> of the jacobian may be playing a part in that. I would like to improve the
> conditioning by using -ksp_diagonal_scale, but adding it does not seem to
> help. The documentation for this option says 'this routine is only used if
> the matrix and preconditioner matrix are the same thing'.
>
> Does that mean the command can only be used with no preconditioner?
>
> http://www.mcs.anl.gov/petsc/**petsc-current/docs/**manualpages/KSP/**
> KSPSetDiagonalScale.html<http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPSetDiagonalScale.html>
>
> All the best,
>
> --
> Colin McAuliffe
> PhD Candidate
> Columbia University
> Department of Civil Engineering and Engineering Mechanics
>
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