From: bangerth Date: Thu, 10 May 2012 16:26:18 +0000 (+0000) Subject: Add some documentation. X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=04c40e8dc7d491573d05b77d5ef5aa81d2c5a2eb;p=dealii-svn.git Add some documentation. git-svn-id: https://svn.dealii.org/trunk@25505 0785d39b-7218-0410-832d-ea1e28bc413d --- diff --git a/deal.II/include/deal.II/numerics/error_estimator.h b/deal.II/include/deal.II/numerics/error_estimator.h index b1068cda2c..61ea08138a 100644 --- a/deal.II/include/deal.II/numerics/error_estimator.h +++ b/deal.II/include/deal.II/numerics/error_estimator.h @@ -157,11 +157,22 @@ namespace hp * *
  • No other boundary conditions are considered. * - * The object describing the boundary conditions is obtained from the - * triangulation. * - * Thanks go to Franz-Theo Suttmeier for clarifications about boundary - * conditions. + * In practice, if you have Robin boundary conditions or are too lazy to + * accurately describe Neumann values, then this is rarely an issue: if you + * don't say anything in the map about a particular part of the boundary then + * the Kelly indicator will simply assume that the solution is correct on + * that part of the boundary and not touch it. Of course, if you have a have + * a Neumann or Robin boundary, that isn't quite true, there is going to be a + * difference between the normal derivative of the numerical solution and the + * Neumann values these normal derivatives should equal. So if we simply + * ignore those parts of the boundary, we'll underestimate the error. In + * practice, this rarely appears to be a problem -- you may not refine the + * cell this time around but you'll probably refine it in the next refinement + * step and everything is good again. After all, for all problems but the + * Laplace equation, the Kelly indicator is only an indicator, not an + * estimator, and so the values it computes are not exact error + * representations anyway. * * *

    Handling of hanging nodes