From 63570aaa27bbea573912eec63051608da472a788 Mon Sep 17 00:00:00 2001 From: wolf Date: Thu, 1 Apr 2004 17:16:11 +0000 Subject: [PATCH] Add some documentation. git-svn-id: https://svn.dealii.org/trunk@8948 0785d39b-7218-0410-832d-ea1e28bc413d --- deal.II/lac/include/lac/petsc_precondition.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/deal.II/lac/include/lac/petsc_precondition.h b/deal.II/lac/include/lac/petsc_precondition.h index b39f97448c..96a019273c 100644 --- a/deal.II/lac/include/lac/petsc_precondition.h +++ b/deal.II/lac/include/lac/petsc_precondition.h @@ -145,7 +145,14 @@ namespace PETScWrappers /** * A class that implements the interface to use the PETSc Block Jacobi - * preconditioner. + * 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 + * 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 + * the matrix for preconditioning. This can be changed, as is explained in the + * relevant section of the PETSc manual, but is not implemented here. * * @author Wolfgang Bangerth, 2004 */ -- 2.39.5