From 6132f93e54b59cbe1ceee9dbb958fc2b964c1dec Mon Sep 17 00:00:00 2001
From: eschnett <eschnett@6ca9aeac-0e4f-0410-a746-fe4df63e9d0c>
Date: Thu, 1 Jul 2010 02:54:21 +0000
Subject: Add documentation

git-svn-id: http://svn.cactuscode.org/arrangements/CactusNumerical/InterpToArray/trunk@18 6ca9aeac-0e4f-0410-a746-fe4df63e9d0c
---
 doc/documentation.tex | 63 +++++++++++++++++++++++++++------------------------
 1 file changed, 33 insertions(+), 30 deletions(-)

diff --git a/doc/documentation.tex b/doc/documentation.tex
index 322776c..8225ebe 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -77,12 +77,12 @@
 \begin{document}
 
 % The author of the documentation
-\author{Erik Schnetter \textless schnetter@aei.mpg.de\textgreater}
+\author{Erik Schnetter \textless schnetter@cct.lsu.edu\textgreater}
 
 % The title of the document (not necessarily the name of the Thorn)
-\title{}
+\title{InterpToArray}
 
-\date{July 15 2004}
+\date{June 30, 2010}
 
 \maketitle
 
@@ -94,44 +94,47 @@
 
 % Add an abstract for this thorn's documentation
 \begin{abstract}
-
+  Interpolate grid functions to grid arrays on a regular grid of
+  locations, so that these can e.g.\ be output more easily.
 \end{abstract}
 
 % The following sections are suggestive only.
 % Remove them or add your own.
 
 \section{Introduction}
+Some post-processing and visualisation tools cannot handle mesh
+refinement or multi-block systems.  These tools then require
+interpolating the result onto a regular, uniform grid.  This is what
+this thorn does.
 
-\section{Physical System}
+InterpToArray can interpolate to 0D, 1D, 2D, and 3D grids.  The
+interpolation result is stored in grid arrays.  These can be either
+replicated or distributed over all processes.  Note that using
+replicated (DISTRIB=constant) grid arrays can require a substantial
+amount of memory on each process.
 
 \section{Numerical Implementation}
+InterpToArray uses standard Cactus interpolators such as PUGHInterp or
+CarpetInterp.
 
 \section{Using This Thorn}
-
-\subsection{Obtaining This Thorn}
-
-\subsection{Basic Usage}
-
-\subsection{Special Behaviour}
-
-\subsection{Interaction With Other Thorns}
-
-\subsection{Examples}
-
-\subsection{Support and Feedback}
-
-\section{History}
-
-\subsection{Thorn Source Code}
-
-\subsection{Thorn Documentation}
-
-\subsection{Acknowledgements}
-
-
-\begin{thebibliography}{9}
-
-\end{thebibliography}
+The variables which should be interpolated are specified by
+parameters; currently, up to 100 variables can be interpolated.
+
+The interpolator and its options are also specified via parameters.
+
+Finally, the locations of the points of the regular grid are also
+specified via parameters.  These grid points are specified via an
+\emph{origin} and \emph{offsets}, and they do not have to be aligned
+with the coordinate axes.  For example, a 2D grid is specified via
+three (real) vectors $x^a$, $di^a$, and $dj^a$, and via its (integer)
+size $ni$ and $nj$.  The coordinates of the grid points are then given
+via
+$$
+x^a(i,j) = x^a + i \cdot di^a + j \cdot dj^a
+$$
+for $0 \le i < ni$ and $0 \le j < nj$.  Grids with other dimensions
+are specified equivalently.
 
 % Do not delete next line
 % END CACTUS THORNGUIDE
-- 
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