[petsc-users] gamg and zero pivots

[Jed Brown]

Matthew Knepley <knepley at gmail.com> writes:
>>At the same time, the first block, as discussed, has
>> these zeros on the diagonal, and can’t use SOR.
>>
>
> Chebyshev/Jacobi is the obvious next try.

Not really; the Chebyshev polynomial exceeds 1 left of the origin, so
it's pretty non-functional on indefinite operators.  Pretending like
Gideon's saddle point problem is positive definite is not a solution.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 818 bytes
Desc: not available
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20150921/723391c8/attachment.pgp>