From 69388aaa81acf679c45a79420159fae6d56d0c74 Mon Sep 17 00:00:00 2001 From: Wolfgang Bangerth Date: Wed, 6 Apr 2011 19:54:38 +0000 Subject: [PATCH] step-21: If the size of a linear system is small, i.e. when the mesh is very coarse, then it is sometimes not sufficient to set a maximum of src.size() CG iterations before the solver in the vmult() function converges. (This is, of course, a result of numerical round-off, since we know that on paper, the CG method converges in at most src.size() steps.) As a consequence, we set the maximum number of iterations equal to the maximum of the size of the linear system and 200. git-svn-id: https://svn.dealii.org/trunk@23563 0785d39b-7218-0410-832d-ea1e28bc413d --- deal.II/doc/news/changes.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/deal.II/doc/news/changes.h b/deal.II/doc/news/changes.h index bac4a0b86e..f62a76a807 100644 --- a/deal.II/doc/news/changes.h +++ b/deal.II/doc/news/changes.h @@ -95,6 +95,14 @@ should be fixed now.

Specific improvements

    +
  1. Fixed: In step-21, the inner iteration would sometimes not converge for +very coarse meshes because of numerical roundoff. This is now fixed by allowing +more than rhs.size() CG iterations if the number of degrees of freedom +is very small. +
    +(Jichao Yin, WB, 2011/04/06) +
  2. +
  3. New: There is now a new function ConditionalOStream::get_stream().
    (WB, 2011/03/09) -- 2.39.5