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git-svn-id: http://svn.cactuscode.org/arrangements/CactusBase/CartGrid3D/trunk@58 c78560ca-4b45-4335-b268-5f3340f3cb52

1 files changed, 30 insertions, 1 deletions

diff --git a/doc/documentation.tex b/doc/documentation.tex
index 5cefc97..6299ed7 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -27,8 +27,37 @@ grid functions with the standard names {\tt x}, {\tt y}, and
 from {\tt grid}.  The coordinates are
 registered with the flesh using the same names "x", "y" 
 and "z". In addition a grid function {\tt r} (registered as
-"r") is provided, containing the radius from the origin.
+"r") is provided, containing the radial coordinate from
+the origin where
+$$
+r = \sqrt{x^2+y^2+z^2}
+$$
 
+{\tt CartGrid3D} registers the lower and upper range of each coordinate
+with the flesh.
+
+\subsection{Symmetries}
+
+If your problem and initial data allow it, {\tt CartGrid3D}
+allows you to enforce either an even or odd parity
+symmetry condition for any grid functions at each
+coordinate axes. For a function $\phi(x,y,z)$,
+even parity symmetry on the $x$-axis means
+$$
+\phi(-x,y,z) = \phi(x,y,z)
+$$
+while odd parity symmetry means
+$$
+\phi(-x,y,z) = -\phi(x,y,z)
+$$
+
+Note that the symmetries will only be enforced if a 
+symmetry domain is chosen (that is, if 
+{\tt domain} is {\tt octant}, {\tt quadrant} or {\tt bitant}).
+
+\subsection{Registering Symmetry Behaviour}
+
+Each grid function can register how it behaves under a coordinate change
 
 
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