[petsc-users] KSP solver increases the solution time

[Jed Brown]

2011/4/26 Alejandro Marcos Aragón <alejandro.aragon at gmail.com>

> As you can see, the second iteration takes more than 40 seconds to solve.
> Could some explain why this is happening and why he number of iterations is
> increasing dramatically between solves?


What has changed between solves? If this is part of a nonlinear problem, it
might have just gotten harder to solve. If the linear system is the same,
the right hand side for the first problem was probably degenerate (roughly
speaking, having significant energy in only a few Krylov modes).
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