Dear PETSc/Tao team, it seems to be that there is a bug in the LMVM matrix class:
In the function MatCreateVecs_LMVM, see, e.g., https://petsc.org/release/src/ksp/ksp/utils/lmvm/lmvmimpl.c.html at line 214. it is not checked if the vectors *L, or *R are NULL. This is, in particular, a problem if this matrix class is combined with the Schur complement matrix class, since MatMult_SchurComplement calls this function with NULL as *R, see, e.g. https://petsc.org/release/src/ksp/ksp/utils/schurm/schurm.c.html at line 66.
I attach a minimal example. You need to modify the paths to the PETSc installation in the makefile.
Best regards Stephan Köhler -- Stephan Köhler TU Bergakademie Freiberg Institut für numerische Mathematik und Optimierung Akademiestraße 6 09599 Freiberg Gebäudeteil Mittelbau, Zimmer 2.07 Telefon: +49 (0)3731 39-3173 (Büro)
Minimal_example_schur_lmvm.tar.gz
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