[petsc-users] schur complement and condition number

[Jed Brown]

2011/3/30 Gong Ding <gdiso at ustc.edu>

> I know the bad condition number comes from a lumped boundary.
> For this boundary, the sum of flux comes from all the boundary elements
> shoule equals to a fixed given flux.
>

Sounds like your problem has a one dimensional null space, have you tried
setting the null space? (See the user's manual section on solving singular
systems or docs for KSPSetNullSpace().)
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