From: Wolfgang Bangerth Date: Sat, 25 Jan 2014 14:43:00 +0000 (+0000) Subject: Augment documentation. X-Git-Tag: v8.2.0-rc1~956 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b63979359800f906e13729d527e841a46eddeefc;p=dealii.git Augment documentation. git-svn-id: https://svn.dealii.org/trunk@32313 0785d39b-7218-0410-832d-ea1e28bc413d --- diff --git a/deal.II/include/deal.II/numerics/solution_transfer.h b/deal.II/include/deal.II/numerics/solution_transfer.h index b37133426a..3c2dd0dbb0 100644 --- a/deal.II/include/deal.II/numerics/solution_transfer.h +++ b/deal.II/include/deal.II/numerics/solution_transfer.h @@ -136,7 +136,7 @@ DEAL_II_NAMESPACE_OPEN *
  • Solution transfer with only refinement. Assume that we have got a * solution vector on the current (original) grid. * Each entry of this vector belongs to one of the - * DoFs of the discretisation. If we now refine the grid then the calling of + * DoFs of the discretization. If we now refine the grid then the calling of * DoFHandler::distribute_dofs() will change at least some of the * DoF indices. Hence we need to store the DoF indices of all active cells * before the refinement. A pointer for each active cell @@ -198,8 +198,36 @@ DEAL_II_NAMESPACE_OPEN * refine_interpolate(in, out)) only be called once. * * + * + *

    Implementation in the context of hp finite elements

    + * + * In the case of hp::DoFHandlers, it is not defined which of the finite elements + * that are part of the hp::FECollection associated with the DoF handler, should + * be considered on cells that are not active (i.e., that have children). This + * is because degrees of freedom are only allocated for active cells and, in fact, + * it is not allowed to set an active_fe_index on non-active cells using + * DoFAccessor::set_active_fe_index(). + * + * It is, thus, not entirely natural what should happen if, for example, a few cells + * are coarsened away. This class then implements the following algorithm: + * - If a cell is refined, then the values of the solution vector(s) are saved before + * refinement on the to-be-refined cell and in the space associated with this + * cell. These values are then interpolated to the finite element spaces of the + * children post-refinement. This may lose information if, for example, the old + * cell used a Q2 space and the children use Q1 spaces, or the information may + * be prolonged if the mother cell used a Q1 space and the children are Q2s. + * - If cells are to be coarsened, then the values from the child cells are + * interpolated to the mother cell using the largest of the child cell spaces. + * For example, if the children of a cell use Q1, Q2 and Q3 spaces, then the + * values from the children are interpolated into a Q3 space on the mother cell. + * After refinement, this Q3 function on the mother cell is then interpolated into + * the space the user has selected for this cell (which may be different from + * Q3, in this example, if the user has set the active_fe_index for a different + * space post-refinement and before calling hp::DoFHandler::distribute_dofs()). + * + * * @ingroup numerics - * @author Ralf Hartmann, 1999 + * @author Ralf Hartmann, 1999, Oliver Kayser-Herold and Wolfgang Bangerth, 2006, 2014 */ template, class DH=DoFHandler > class SolutionTransfer