From 019e2742dbd1aba84dadd6c9cbc87e948b8f75c8 Mon Sep 17 00:00:00 2001 From: Wolfgang Bangerth Date: Fri, 30 Mar 2018 23:37:00 -0600 Subject: [PATCH] Update documentation of FE_FaceQ/P. In particular, mention what happens when you use this element as part of an FESystem element. --- include/deal.II/fe/fe_face.h | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/include/deal.II/fe/fe_face.h b/include/deal.II/fe/fe_face.h index 8f50d417ef..0072d572ed 100644 --- a/include/deal.II/fe/fe_face.h +++ b/include/deal.II/fe/fe_face.h @@ -25,7 +25,7 @@ DEAL_II_NAMESPACE_OPEN /** - * A finite element, which is a tensor product polynomial on each face and + * A finite element that is a tensor product polynomial on each face and * undefined in the interior of the cells. The basis functions on the faces * are Lagrange polynomials based on the support points of the * (dim-1)-dimensional Gauss--Lobatto quadrature rule. For element degree one @@ -39,10 +39,13 @@ DEAL_II_NAMESPACE_OPEN * demonstrated in the step-51 tutorial program. * * @note Since this element is defined only on faces, only FEFaceValues and - * FESubfaceValues will be able to extract reasonable values from any face - * polynomial. In order to make the use of FESystem simpler, using a (cell) - * FEValues object will not fail using this finite element space, but all - * shape function values extracted will be equal to zero. + * FESubfaceValues will provide useful information. On the other hand, if you + * use this element with FEValues for cell integration, then the values + * and derivatives of shape functions will have invalid values and will not + * likely produce anything useful. In order to make the use of this element + * as part of an FESystem simpler, using a (cell) FEValues object will not fail + * outright, but those components of shape functions of the combined element + * that correspond to FE_FaceQ will have the invalid values mentioned above. * * @ingroup fe * @author Guido Kanschat, Martin Kronbichler @@ -427,7 +430,7 @@ private: /** - * A finite element, which is a Legendre element of complete polynomials on + * A finite element that is a Legendre element of complete polynomials on * each face (i.e., it is the face equivalent of what FE_DGP is on cells) and * undefined in the interior of the cells. The basis functions on the faces * are from Polynomials::Legendre. @@ -438,10 +441,13 @@ private: * hybridizes methods can be found in the step-51 tutorial program. * * @note Since this element is defined only on faces, only FEFaceValues and - * FESubfaceValues will be able to extract reasonable values from any face - * polynomial. In order to make the use of FESystem simpler, using a (cell) - * FEValues object will not fail using this finite element space, but all - * shape function values extracted will be equal to zero. + * FESubfaceValues will provide useful information. On the other hand, if you + * use this element with FEValues for cell integration, then the values + * and derivatives of shape functions will have invalid values and will not + * likely produce anything useful. In order to make the use of this element + * as part of an FESystem simpler, using a (cell) FEValues object will not fail + * outright, but those components of shape functions of the combined element + * that correspond to FE_FaceP will have the invalid values mentioned above. * * @ingroup fe * @author Martin Kronbichler @@ -540,6 +546,7 @@ private: /** * FE_FaceP in 1D, i.e., with degrees of freedom on the element vertices. + * See the documentation of the general template for more information. */ template class FE_FaceP<1,spacedim> : public FE_FaceQ<1,spacedim> -- 2.39.5