From 1efcc4febfec765124dc1d321b8a29fae8ee4530 Mon Sep 17 00:00:00 2001 From: Wolfgang Bangerth Date: Fri, 19 Jan 2018 17:37:19 -0700 Subject: [PATCH] Update a comment for PETScWrappers::PreconditionBlockJacobi. --- include/deal.II/lac/petsc_precondition.h | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/include/deal.II/lac/petsc_precondition.h b/include/deal.II/lac/petsc_precondition.h index 954d55ce30..f73a83946c 100644 --- a/include/deal.II/lac/petsc_precondition.h +++ b/include/deal.II/lac/petsc_precondition.h @@ -185,9 +185,15 @@ namespace PETScWrappers /** * A class that implements the interface to use the PETSc Block Jacobi - * preconditioner. The blocking structure of the matrix is determined by the - * association of degrees of freedom to the individual processors in an MPI- - * parallel job. If you use this preconditioner on a sequential job (or an + * preconditioner. PETSc defines the term "block Jacobi" as a preconditioner + * in which it looks at a number of diagonal blocks of the matrix and then + * defines a preconditioner in which the preconditioner matrix has the same + * block structure as only these diagonal blocks, and each diagonal block + * of the preconditioner is an approximation of the inverse of the + * corresponding block of the original matrix. + * The blocking structure of the matrix is determined by the + * association of degrees of freedom to the individual processors in an + * MPI-parallel job. If you use this preconditioner on a sequential job (or an * MPI job with only one process) then the entire matrix is the only block. * * By default, PETSc uses an ILU(0) decomposition of each diagonal block of -- 2.39.5