From fbc6acdd5bcb013d14ce7a2e3a929d47a6177539 Mon Sep 17 00:00:00 2001 From: Wolfgang Bangerth Date: Thu, 14 Apr 2011 13:34:07 +0000 Subject: [PATCH] Add one more paragraph. git-svn-id: https://svn.dealii.org/trunk@23595 0785d39b-7218-0410-832d-ea1e28bc413d --- deal.II/examples/step-46/doc/intro.dox | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/deal.II/examples/step-46/doc/intro.dox b/deal.II/examples/step-46/doc/intro.dox index b3bd8450c1..a9f9eb426b 100644 --- a/deal.II/examples/step-46/doc/intro.dox +++ b/deal.II/examples/step-46/doc/intro.dox @@ -377,6 +377,17 @@ solid cell is refined, yielding the following code: } } @endcode + +The call constraints.add_line(t) tells the +ConstraintMatrix to start a new constraint for degree of freedom +t of the form $x_t=\sum_{l=0}^{N-1} c_{tl} x_l + +b_t$. Typically, one would then proceed to set individual coefficients +$c_{tl}$ to nonzero values (using ConstraintMatrix::add_entry) or set +$b_t$ to something nonzero (using +ConstraintMatrix::set_inhomogeneity); doing nothing as above, funny as +it looks, simply leaves the constraint to be $x_t=0$, which is exactly +what we need in the current context. + Note that there are cases where this may yield incorrect results: notably, once we find a solid neighbor child to a current fluid cell, we assume that all neighbor children on the common face are in the -- 2.39.5