[petsc-users] Is it possible to use -snes_ksp_ew in the framework of KSP?

[Song Gao]

Hello,

We are working on a legacy codes which solves the NS equations. The codes
take control of newton iterations itself and use KSP to solve the linear
system.

We modified the codes, used SNES to control the newton iteration and
changed the code to matrix free fashion. But the legacy codes did a lot of
other things between two newton iterations (such as output solution, update
variables....). I know we could use linesearchpostcheck but it is
difficulty to do that correctly. Therefore, we decide to go back to the KSP
framework but still use matrix free.

When using SNES, we always use the runtime option -snes_ksp_ew, we observe
that for some test cases, the residual stalls without -snes_ksp_ew, but
converges with-snes_ksp_ew. So I'm thinking if it is possible to
use -snes_ksp_ew in KSP? Thanks in advance.
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