]> https://gitweb.dealii.org/ - dealii-svn.git/commitdiff
Fix energy, again.
authorbangerth <bangerth@0785d39b-7218-0410-832d-ea1e28bc413d>
Wed, 15 Nov 2006 05:37:10 +0000 (05:37 +0000)
committerbangerth <bangerth@0785d39b-7218-0410-832d-ea1e28bc413d>
Wed, 15 Nov 2006 05:37:10 +0000 (05:37 +0000)
git-svn-id: https://svn.dealii.org/trunk@14194 0785d39b-7218-0410-832d-ea1e28bc413d

deal.II/examples/step-25/doc/results.dox

index 9e5c1183bb1f76799ff8611222dfc1d94533ca45..8def52582a65395b78fc5e2461467d3a68cf12ae 100644 (file)
@@ -122,8 +122,11 @@ is defined as
 @f[
   E(t) = \frac 12 \int_\Omega \left(\frac{\partial u}{\partial
   t}\right)^2
-  + \left(\nabla u\right)^2 - 2 \cos u \; dx.
+  + \left(\nabla u\right)^2 + 2 (1-\cos u) \; dx.
 @f]
+(The constant $2$ appears in the formula to ensure that all contributions to
+the energy are positive, and so that decaying solutions have finite energy on
+unbounded domains.)
 
 Beyond this, clearly, adaptivity (i.e. time-adaptive grids) would be of
 interest to problems like these. Their complexity leads us to leave this out

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