PCVPBJACOBI#

Variable size point block Jacobi preconditioner

Notes#

See PCJACOBI for point Jacobi preconditioning, PCPBJACOBI for fixed point block size, and PCBJACOBI for large size blocks

This works for MATAIJ matrices

Uses dense LU factorization with partial pivoting to invert the blocks; if a zero pivot is detected a PETSc error is generated.

One must call MatSetVariableBlockSizes() to use this preconditioner

Developer Notes#

This should support the PCSetErrorIfFailure() flag set to PETSC_TRUE to allow the factorization to continue even after a zero pivot is found resulting in a Nan and hence terminating KSP with a KSP_DIVERGED_NANORINF allowing a nonlinear solver/ODE integrator to recover without stopping the program as currently happens.

Perhaps should provide an option that allows generation of a valid preconditioner even if a block is singular as the PCJACOBI does.

See Also#

KSP: Linear System Solvers, MatSetVariableBlockSizes(), PCCreate(), PCSetType(), PCType, PC, PCJACOBI, PCPBJACOBI, PCBJACOBI

Level#

beginner

Location#

src/ksp/pc/impls/vpbjacobi/vpbjacobi.c


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