From d5b023689a29b46dc27ea6bb183005b4bb813a23 Mon Sep 17 00:00:00 2001 From: bangerth Date: Wed, 24 Oct 2012 15:38:38 +0000 Subject: [PATCH] Augment documentation. git-svn-id: https://svn.dealii.org/trunk@27192 0785d39b-7218-0410-832d-ea1e28bc413d --- .../include/deal.II/lac/precondition_block.h | 23 ++++++++++++------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/deal.II/include/deal.II/lac/precondition_block.h b/deal.II/include/deal.II/lac/precondition_block.h index 082228dfd4..e1519e6334 100644 --- a/deal.II/include/deal.II/lac/precondition_block.h +++ b/deal.II/include/deal.II/lac/precondition_block.h @@ -35,16 +35,23 @@ class PreconditionBlockJacobi; * Base class for actual block preconditioners. This class assumes the * MATRIX consisting of invertible blocks of @p blocksize on * the diagonal and provides the inversion of the diagonal blocks of - * the matrix. NOT only block diagonal matrices are allowed but all + * the matrix. It is not necessary for this class that the matrix be + * block diagonal; rather, it applies to * matrices of arbitrary structure with the minimal property of having - * invertible blocks on the diagonal! Still the matrix must have - * access to single matrix entries. therefore, BlockMatrixArray is not - * a possible matrix class. + * invertible blocks on the diagonal. Still the matrix must have + * access to single matrix entries. Therefore, BlockMatrixArray and similar + * classes are not a possible matrix class template arguments. * - * This block matrix structure is given e.g. for the DG method for the - * transport equation. For a downstream numbering the matrices even - * have got a block lower left matrix structure, i.e. the matrices are - * empty above the diagonal blocks. + * The block matrix structure used by this class is given, e.g., for + * the DG method for the transport equation. For a downstream + * numbering the matrices even have got a block lower left matrix + * structure, i.e. the matrices are empty above the diagonal blocks. + * + * @note This class is intended to be used for matrices whose structure + * is given by local contributions from disjoint cells, such as for DG + * methods. It is not intended for problems where the block structure + * results from different physical variables such as in the Stokes + * equations considered in step-22. * * For all matrices that are empty above and below the diagonal blocks * (i.e. for all block diagonal matrices) the @p BlockJacobi -- 2.39.5