[petsc-users] Near nullspace lost in fieldsplit

[Jeremy Theler (External)]

Hi all

Because of a combination of settings, our code passes through this line:

https://gitlab.com/petsc/petsc/-/blob/main/src/ksp/pc/impls/fieldsplit/fieldsplit.c?ref_type=heads#L692

i.e. the matrices associated with each of the sub-KSPs of a fieldsplit are destroyed and then re-created later.
The thing is that one of these destroyed matrices had a near nullspace attached, which is lost because the new matrix does not have it anymore.

Is this a bug or are we missing something?
I'll need some time to come up with a MWE showing how the near nullspace is lost, but if its needed I can take a stab at it.

--
jeremy

[https://gitlab.com/uploads/-/system/project/avatar/13882401/PETSc_RBG-logo.png]<https://gitlab.com/petsc/petsc/-/blob/main/src/ksp/pc/impls/fieldsplit/fieldsplit.c?ref_type=heads#L692>
src/ksp/pc/impls/fieldsplit/fieldsplit.c · main · PETSc / petsc · GitLab<https://gitlab.com/petsc/petsc/-/blob/main/src/ksp/pc/impls/fieldsplit/fieldsplit.c?ref_type=heads#L692>
PETSc, pronounced PET-see (the S is silent), is a suite of data structures and routines for the scalable (parallel) solution of scientific applications modeled by partial differential equations.
gitlab.com

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