[petsc-users] -pc_fieldsplit_schur_precondition

Matthew Knepley knepley at gmail.com
Wed Dec 4 07:57:44 CST 2019

On Wed, Dec 4, 2019 at 8:38 AM Cotter, Colin J <colin.cotter at imperial.ac.uk>

> >The action of the Schur complement is always MatMult() KSPSolve()
> MatMult().
> OK, so when pc_fieldsplit_schur_precondition is set to full, what actually
> happens?

It computes the operator explicitly:


Usually you use LU, which means making B dense, then doing MatMatSolve(),
and then MatMatMult() for sparse.



What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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