From 0374589ec830f9ae3f4ac5413ae52fc847a0b0d9 Mon Sep 17 00:00:00 2001 From: Guido Kanschat Date: Mon, 5 Feb 2001 15:11:14 +0000 Subject: [PATCH] no mass matrix without quadrature git-svn-id: https://svn.dealii.org/trunk@3860 0785d39b-7218-0410-832d-ea1e28bc413d --- deal.II/deal.II/include/numerics/matrices.h | 61 ++++----------------- 1 file changed, 12 insertions(+), 49 deletions(-) diff --git a/deal.II/deal.II/include/numerics/matrices.h b/deal.II/deal.II/include/numerics/matrices.h index c81d70f4bd..93bffa99be 100644 --- a/deal.II/deal.II/include/numerics/matrices.h +++ b/deal.II/deal.II/include/numerics/matrices.h @@ -27,6 +27,8 @@ template class MGDoFHandler; template class FEValues; template class Equation; +//TODO: Update documentation on mass matrices + /** * Provide a class which assembles certain standard matrices for a given * triangulation, using a given finite element and a quadrature formula. @@ -59,23 +61,15 @@ template class Equation; * are the basis functions of the finite element space given. * This function uses the @ref{MassMatrix} class. * - * Two ways to create this matrix are offered. The first one uses - * numerical quadrature and the @ref{MassMatrix} class. In this case, - * a coefficient may be given to evaluate - * $m_{ij} = \int_\Omega a(x) \phi_i(x) \phi_j(x) dx$ instead. - * This way of setting up the mass matrix is quite general, but has - * some drawbacks, see the documentation of the @ref{MassMatrix} class. - * - * The other way uses exact integration, as offered by the finite - * element class used. This way you can avoid quadrature errors and - * the assemblage is much faster. However, no coefficient can be - * given. - * - * Note that the effect of the two ways of setting up the mass - * matrix is not the same if you use finite elements which are - * composed of several subelements. In this case, using the - * quadrature free way (without coefficient) results in a matrix - * which does not couple the subelements, as described in the + * The mass matrix is generated using a numerical quadrature rule + * and the @ref{MassMatrix} class. A coefficient may + * be specified to evaluate $m_{ij} = \int_\Omega a(x) \phi_i(x) + * \phi_j(x) dx$ instead. This way of setting up the mass matrix is + * quite general, but has some drawbacks. See the documentation of + * the @ref{MassMatrix} class. + * + * Update documentation on mass matrices for FESystem!!! + * * @ref{FESystem}@p{::get_local_mass_matrix} documentation, while the * way using quadrature sets up the full matrix, i.e. with the * cross coupling of shape functions belonging to different subelements. @@ -174,8 +168,7 @@ template class Equation; * @ref{DoFHandler} object the last time that the degrees of freedom were * distributed on the triangulation. * - * @author Wolfgang Bangerth, 1998 - */ + * @author Wolfgang Bangerth, 1998 */ template class MatrixCreator { @@ -199,14 +192,6 @@ class MatrixCreator * coefficient is given, it is assumed * to be constant one. * - * If the coefficient is constant, it - * may be more adequate to use the - * functions assembling the mass matrix - * without quadrature. However, the - * two functions have different effects - * for finite elements composed of - * several subobjects. - * * See the general doc of this class * for more information. */ @@ -239,28 +224,6 @@ class MatrixCreator Vector &rhs_vector, const Function *a = 0); - /** - * Create the mass matrix by exact - * evaluation without using a quadrature - * formula. - * - * No right hand side may be created using - * this function. See the general doc of - * this class for more information. - * - * It is assumed that the matrix already - * has the right size. The mass matrix - * elements are summed up to the values - * previously in the matrix, so if you want - * the pure mass matrix, you have to clear - * the matrix beforehand. - * - * See the general doc of this class - * for more information. - */ - static void create_mass_matrix (const DoFHandler &dof, - SparseMatrix &matrix); - /** * Assemble the mass matrix and a right * hand side vector along the boundary. -- 2.39.5