* document Gowdy-wave model (this was missing from the thorn guide)

* add a new feature that any vacuum non-cosmological-constant solution
  can be Lorentz-boosted by any 3-velocity
  (previously, Kerr/Kerr-Schild had the ability to do a z-axis boost,
  but the new code works for most of the models, and can boost in any direction)
* general cleanup of most of the individual models to systematize
  comment conventions for subroutine arguments: input arguments,
  output arguments, static local variables, local variables, parameters
* cleanup comments in various places to describe conformal factor
  being passed to/from individual models (this was in the code before,
  but not consistently documented)
* various other cleanups in documentation

There should be no change in the operation of any of the existing models.


git-svn-id: http://svn.einsteintoolkit.org/cactus/EinsteinInitialData/Exact/trunk@162 e296648e-0e4f-0410-bd07-d597d9acff87

2 files changed, 271 insertions, 101 deletions

diff --git a/doc/documentation.tex b/doc/documentation.tex
index 3ea8f73..41c4e4e 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -98,11 +98,12 @@
 % Add all definitions used in this documentation here 
 %   \def\mydef etc
 
+\def\thorn#1{{\bf #1}}
+\def\defn#1{{\bf #1}}
+
 % force a line break in a itemize/description/enumerate environment
 \def\forcelinebreak{\mbox{}\\[-\baselineskip]}
 
-\def\defn#1{{\bf #1}}
-
 \def\eg{e.g.\hbox{}}
 \def\ie{i.e.\hbox{}}
 \def\etal{{\it et~al.\/\hbox{}}}
@@ -110,9 +111,11 @@
 \def\Nb{N.b.\hbox{}}
 
 % math stuff
+\def\dfrac#1#2{{\displaystyle\frac{#1}{#2}}}
+\def\tfrac#1#2{{\textstyle   \frac{#1}{#2}}}
 \def\diag{\text{diag}}
 \def\Gaussian{{\sf G}}
-\def\half{{\textstyle \frac{1}{2}}}
+\def\half{\tfrac{1}{2}}
 \def\sech{\text{sech}}
 
 % Add an abstract for this thorn's documentation
@@ -122,9 +125,10 @@ of exact spacetimes/coordinates, and even some non-Einstein
 spcetimes/coordinates.  It's easy to add more spacetimes/coordinates:
 all you have to supply is the 4-metric $g_{ab}$ and the inverse 4-metric
 $g^{ab}$ (this thorn automagically calculates all the ADM variables
-from these). Optionally, the ADM variables can be calculated on an
+from these).  Optionally, any 4-metric can be Lorentz-boosted in any
+direction.  As another option, the ADM variables can be calculated on an
 arbitrary slice through the spacetime, using arbitrary coordinates on
-the slice. Given a lapse and shift, the slice can be evolved through
+the slice.  Given a lapse and shift, the slice can be evolved through
 the exact solution, in order to check on an evolution code, or in
 order to test gauge conditions without the need for an evolution code.
 \end{abstract}
@@ -145,6 +149,12 @@ makes this thorn set up the ADM variables at \verb|CCTK_PRESTEP|
 every time step of an evolution, so you get an exact {\em spacetime\/},
 not just a single slice.
 
+There is an option to Lorentz-boost any vacuum model
+(more precisely any model which doesn't set the stress-energy tensor;
+see table~\ref{AEIThorns/Exact/tab-all-models} and
+section~\ref{AEIThorns/Exact/sect-Lorentz-boosting-a-spacetime}
+for details) in any direction.
+
 There is also a more general option to set up the ADM variables
 on an arbitrary slice through the spacetime, using arbitrary
 coordinates on the slice.  Given a lapse and shift computed by some
@@ -166,7 +176,8 @@ see the comments there for details.
 
 \subsection{Models Supported}
 
-The following models are currently supported:%%%
+Table~\ref{AEIThorns/Exact/tab-all-models} shows the models supported
+by thorn~\thorn{Exact}.%%%
 \footnote{%%%
 	 To add a new model, you have to modify a
 	 number of files in this thorn.  See the file
@@ -175,90 +186,110 @@ The following models are currently supported:%%%
 	 what to do.  Please follow the naming conventions
 	 given in the next subsection.
 	 }%%%
-\begin{description}
-\item[Minkowski spacetime]\forcelinebreak
-	\begin{description}
-	\item[{\tt "Minkowski"}]
-		Minkowski spacetime
-	\item[{\tt "Minkowski/shift"}]
-		Minkowski spacetime with time-dependent shift vector
-	\item[{\tt "Minkowski/funny"}]
-		Minkowski spacetime in non-trivial spatial coordinates
-	\item[{\tt "Minkowski/gauge wave"}]
-		Minkowski spacetime in gauge-wave coordinates
-	\item[{\tt "Minkowski/conf wave"}]
-		Minkowski spacetime with sinus in conformal factor
-	\end{description}
-\item[Black hole spacetimes]\forcelinebreak
-	\begin{description}
-	\item[{\tt "Schwarzschild/EF"}]
-		Schwarzschild spacetime in Eddington-Finkelstein coordinates
-	\item[{\tt "Schwarzschild/PG"}]
-		Schwarzschild spacetime in Painlev\'{e}-Gullstrand coordinates
-		(these have a flat 3-metric)
-	\item[{\tt "Schwarzschild/Novikov"}]
-		Schwarzschild spacetime in Novikov coordinates
-	\item[{\tt "Kerr/Boyer-Lindquist"}]
-		Kerr spacetime in Boyer-Lindquist coordinates
-	\item[{\tt "Kerr/Kerr-Schild"}]
-		Kerr spacetime in Kerr-Schild coordinates
-	\item[{\tt "Schwarzschild-Lemaitre"}]
-		Schwarzschild-Lemaitre spacetime
-		(Schwarzschild black hole with a cosmological constant)
-	\item[{\tt "multi-BH"}]
-		Majumdar-Papapetrou or Kastor-Traschen
-		maximally-charged (extreme Reissner-Nordstrom)
-		multi-BH solutions
-	\item[{\tt "Alvi"}]
-		Alvi post-Newtonian 2BH spacetime (not fully implemented yet)
-	\item[{\tt "Thorne-fakebinary"}]
-		Thorne's ``fake binary'' spacetime (non-Einstein)
-	\end{description}
-\item[Cosmological spacetimes]\forcelinebreak
-	\begin{description}
-	\item[{\tt "Lemaitre"}]
-		Lemaitre-type spacetime
-	\item[{\tt "Robertson-Walker"}]
-		Robertson-Walker spacetime
-	\item[{\tt "de Sitter"}]
-		de~Sitter spacetime
-	\item[{\tt "de Sitter+Lambda"}]
-		de~Sitter spacetime with cosmological constant
-	\item[{\tt "anti-de Sitter+Lambda"}]
-		anti-de~Sitter spacetime with cosmological constant
-	\item[{\tt "Bianchi I"}]
-		approximate Bianchi type~I spacetime
-	\item[{\tt "Goedel"}]
-		G\"{o}del spacetime
-	\item[{\tt "Bertotti"}]
-		Bertotti spacetime
-	\item[{\tt "Kasner"}]
-		Kasner-like spacetime
-	\item[{\tt "Kasner-axisymmetric"}]
-		axisymmetric Kasner spacetime
-	\item[{\tt "Kasner-generalized"}]
-		generalized Kasner spacetime
-	\item[{\tt "Milne"}]
-		Milne spacetime for pre-big-bang cosmology
-	\end{description}
-\item[Miscellaneous spacetimes]\forcelinebreak
-	\begin{description}
-	\item[{\tt "boost-rotation symmetric"}]
-		boost-rotation symmetric spacetime
-	\item[{\tt "bowl"}]
-		bowl (``bag of gold'') spacetime (non-Einstein)
-	\item[{\tt "constant density star"}]
-		constant density (Schwarzschild) star
-	\end{description}
-\end{description}
-
-As a general policy, this thorn includes only cases where the full
-4-metric $g_{ab}$ (and its inverse, although we could probably dispense
-with that if needed) is known throughout the spacetime.  Cases where
-this is only known on one specific slice, should live in separate
-initial data thorns.
-
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+{}  As a general policy, this thorn includes only cases where the full
+4-metric $g_{ab}$ (and its inverse, although we could dispense with
+that if needed) is known throughout the spacetime.  Cases where this
+is only known on one specific slice, should live in separate initial
+data thorns.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{table}[htbp]
+\begin{center}
+\hyphenpenalty=10000	% forbid hyphenation
+\begin{tabular}{@{\qquad}lcp{80mm}}
+Model Name
+	& $T_{\mu\nu}$?
+		& Description						\\
+\hline %----------------------------------------------------------------
+%
+\multicolumn{3}{l}{\bf Minkowski spacetime}				\\
+{\tt "Minkowski"}
+	& --	& Minkowski spacetime					\\
+{\tt "Minkowski/shift"}
+	& --	& Minkowski spacetime with time-dependent shift vector	\\
+{\tt "Minkowski/funny"}
+	& --	& Minkowski spacetime in non-trivial spatial coordinates\\
+{\tt "Minkowski/gauge wave"}
+	& --	& Minkowski spacetime in gauge-wave coordinates		\\
+{\tt "Minkowski/conf wave"}
+	& --	& Minkowski spacetime with $\sin$ in conformal factor	\\[1ex]
+%
+\multicolumn{3}{l}{\bf Black hole spacetimes}				\\
+{\tt "Schwarzschild/EF"}
+	& --	& Schwarzschild spacetime
+		  in Eddington-Finkelstein coordinates			\\
+{\tt "Schwarzschild/PG"}
+	& --	& Schwarzschild spacetime in Painlev\'{e}-Gullstrand
+		  coordinates (these have a flat 3-metric)		\\
+{\tt "Schwarzschild/Novikov"}
+	& --	& Schwarzschild spacetime in Novikov coordinates	\\
+{\tt "Kerr/Boyer-Lindquist"}
+	& --	& Kerr spacetime in Boyer-Lindquist coordinates		\\
+{\tt "Kerr/Kerr-Schild"}
+	& --	& Kerr spacetime in Kerr-Schild coordinates		\\
+{\tt "Schwarzschild-Lemaitre"}
+	& Yes	& Schwarzschild-Lemaitre spacetime (Schwarzschild
+		  black hole with a cosmological constant)		\\
+{\tt "multi-BH"}
+	& --	& Majumdar-Papapetrou or Kastor-Traschen
+		  maximally-charged (extreme Reissner-Nordstrom)
+		  multi-BH solutions					\\
+{\tt "Alvi"}
+	& --	& Alvi post-Newtonian 2BH spacetime
+		  (not fully implemented yet)				\\
+{\tt "Thorne-fakebinary"}
+	& --	& Thorne's ``fake binary'' spacetime (non-Einstein)	\\[1ex]
+%
+\multicolumn{3}{l}{\bf Cosmological spacetimes}				\\
+{\tt "Lemaitre"}
+	& Yes	& Lemaitre-type spacetime				\\
+{\tt "Robertson-Walker"}
+	& Yes	& Robertson-Walker spacetime				\\
+{\tt "de Sitter"}
+	& Yes	& de~Sitter spacetime					\\
+{\tt "de Sitter+Lambda"}
+	& Yes	& de~Sitter spacetime with cosmological constant	\\
+{\tt "anti-de Sitter+Lambda"}
+	& Yes	& anti-de~Sitter spacetime with cosmological constant	\\
+{\tt "Bianchi I"}
+	& --	& approximate Bianchi type~I spacetime			\\
+{\tt "Goedel"}
+	& --	& G\"{o}del spacetime					\\
+{\tt "Bertotti"}
+	& Yes	& Bertotti spacetime					\\
+{\tt "Kasner"}
+	& Yes	& Kasner-like spacetime					\\
+{\tt "Kasner-axisymmetric"}
+	& --	& axisymmetric Kasner spacetime				\\
+{\tt "Kasner-generalized"}
+	& Yes	& generalized Kasner spacetime				\\
+{\tt "Gowdy-wave"}
+	& --	& Gowdy metric (polarized wave in an expanding universe)\\
+{\tt "Milne"}
+	& --	& Milne spacetime for pre-big-bang cosmology		\\[1ex]
+%
+\multicolumn{3}{l}{\bf Miscellaneous spacetimes}			\\
+{\tt "boost-rotation symmetric"}
+	& --	& boost-rotation symmetric spacetime			\\
+{\tt "bowl"}
+	& --	& bowl (``bag of gold'') spacetime (non-Einstein)	\\
+{\tt "constant density star"}
+	& Yes	& constant density (Schwarzschild) star			%%%\\
+\end{tabular}
+\end{center}
+\caption{
+	This table shows all the models currently supported by
+	thorn \thorn{Exact}.  The $T_{\mu\nu}$ column shows which
+	models set the Cactus stress-energy tensor; as discussed in
+	section~\ref{AEIThorns/Exact/cosmological-constant+stress-energy-tensor}
+	this includes both all non-vacuum models and all models
+	with a cosmological constant.
+	}
+\label{AEIThorns/Exact/tab-all-models}
+\end{table}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 \subsection{Naming Conventions}
 
@@ -305,6 +336,7 @@ REAL Schwarzschild_EF__mass "Schwarzschild/EF: BH mass"
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 \subsection{The Cosmological Constant and the Stress-Energy Tensor}
+\label{AEIThorns/Exact/cosmological-constant+stress-energy-tensor}
 
 A number of these models have a cosmological constant.  To use these
 with the Cactus code (which generally is written for the case of no
@@ -315,7 +347,7 @@ tensor.
 
 This thorn uses the standard Cactus ``\verb|CalcTmunu|'' interface
 for introducing terms into the stress-energy tensor.  See Ian Hawke's
-documentation for the {\bf ADMCoupling} thorn for details.
+documentation for the \thorn{ADMCoupling} thorn for details.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
@@ -330,6 +362,112 @@ omissions here.  Caveat Lector!
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
+\section{Lorentz-Boosting a Spacetime}
+\label{AEIThorns/Exact/sect-Lorentz-boosting-a-spacetime}
+
+For any of the models which don't set the stress-energy tensor
+(\ie{} which are vacuum and have no cosmological constant;
+see section~\ref{AEIThorns/Exact/cosmological-constant+stress-energy-tensor}
+and table~\ref{AEIThorns/Exact/tab-all-models} for details),%%%
+\footnote{%%%
+	 Only $g_{ab}$ and $g^{ab}$ are transformed, not the
+	 stress-energy tensor, which is why this only works
+	 for models which don't set the stress-energy tensor.
+	 }%%%
+{} you can optionally Lorentz-boost the model by a specified 3-velocity
+$v^i$.  The parameters for this are \verb|boost_vx|, \verb|boost_vy|,
+and \verb|boost_vz|.
+
+We define the Cactus spacetime coordinates to be $(t,x^i)$,
+while the model is at rest in coordinates $(T,X^i)$.  The model's
+``origin'' $X^i = 0$ is located at the Cactus coordinates $x^i = v^i t$.  
+
+The boost Lorentz transformation is defined by
+\begin{equation}
+\renewcommand{\arraystretch}{1.333}
+\begin{array}{lcl}
+T		& = &	\gamma (t - \eta_{ij} v^i x^j)		\\
+X^i_\parallel	& = &	\gamma (x^i_\parallel - v^i t)		\\
+X^i_\perp	& = &	x^i_\perp				%%%\\
+\end{array}
+\end{equation}
+and the inverse transformation by
+\begin{equation}
+\renewcommand{\arraystretch}{1.333}
+\begin{array}{lcl}
+t		& = &	\gamma (T + \eta_{ij} v^i X^j)		\\
+x^i_\parallel	& = &	\gamma (X^i_\parallel + v^i T)		\\
+x^i_\perp	& = &	X^i_\perp				%%%\\
+\end{array}
+\end{equation}
+where $\gamma \equiv (1 - v^2)^{-1/2}$ is the usual Lorentz factor,
+$\eta_{ij}$ is the flat metric, and $\parallel$ and $\perp$ refer
+to the (flat-space) components of $x^i$ parallel and perpendicular
+to $v^i$, respectively.
+
+In more detail, define the unit vector $n^i = v^i / \sqrt{\eta_{jk} v^j v^k}$
+and the (flat-space) projection operators
+\begin{equation}
+\renewcommand{\arraystretch}{1.333}
+\begin{array}{lclcl}
+\parallel^i{}\!_j
+		& = &	\eta_{jk} n^i n^k				\\
+		& \equiv &
+			n^i n_j
+			\qquad
+			\hbox{(using $\eta_{ij}$ to raise/lower indices)}
+									\\
+\perp^i{}\!_j	& = &	\delta^i{}_j - \parallel^i{}\!_j		%%%\\
+\end{array}
+\end{equation}
+Then the Lorentz transformations are
+\begin{equation}
+\renewcommand{\arraystretch}{1.333}
+\begin{array}{lcl}
+T	& = &	\gamma (t - \eta_{ij} v^i x^j)				\\
+X^i	& = &	\gamma (\parallel^i{}\!_j x^j - v^i t)
+		+ \perp^i{}\!_j x^j					%%%\\
+\end{array}
+\end{equation}
+and
+\begin{equation}
+\renewcommand{\arraystretch}{1.333}
+\begin{array}{lcl}
+t	& = &	\gamma (T + \eta_{ij} v^i X^j)				\\
+x	& = &	\gamma (\parallel^i{}\!_j X^j + v^i T)
+		+ \perp^i{}\!_j X^j					%%%\\
+\end{array}
+\end{equation}
+so their coordinate partial derivatives for transforming $g_{ab}$
+and $g^{ab}$ are
+\begin{equation}
+\renewcommand{\arraystretch}{2.5}
+\begin{array}{lcl@{\qquad\qquad\qquad}lcl}
+\dfrac{\partial T}{\partial t}		& = &	\gamma
+	&
+\dfrac{\partial T}{\partial x^j}	& = &	- \gamma v^j		\\
+\dfrac{\partial X^i}{\partial t}	& = &	- \gamma v^i
+	&
+\dfrac{\partial X^i}{\partial x^j}	& = &	\gamma \parallel^i{}\!_j
+						+ \perp^i{}\!_j		%%%\\
+\end{array}
+\end{equation}
+and
+\begin{equation}
+\renewcommand{\arraystretch}{2.5}
+\begin{array}{lcl@{\qquad\qquad\qquad}lcl}
+\dfrac{\partial t}{\partial T}		& = &	\gamma
+	&
+\dfrac{\partial t}{\partial X^j}	& = &	\gamma v^j		\\
+\dfrac{\partial x^i}{\partial T}	& = &	\gamma v^i
+	&
+\dfrac{\partial x^i}{\partial X^j}	& = &	\gamma \parallel^i{}\!_j
+						+ \perp^i{}\!_j		%%%\\
+\end{array}
+\end{equation}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
 \section{Minkowski Spacetime}
 
 This thorn can set up Minkowski spacetime using several different
@@ -429,10 +567,12 @@ conditions, to see whether the code is able to cope with that.
 The tricky part is to make the wave fit the grid exactly (otherwise the
 periodic boundary wouldn't make sence), especially in the diagonal case.
 
-\subsection{Minkowski Spacetime with sinus in conformal factor}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\subsection{Minkowski Spacetime with $\sin$ term in conformal factor}
 
-This spacetime just puts a sinus in the conformal factor and the metric
-is calculated to be Minkowski.\\
+\verb|Exact::exact_model = "Minkowski/conf wave"| specifies Minkowski
+spacetime with a $\sin$~term in the Cactus static conformal factor.
 You have three parameters:
 \begin{itemize}
  \item Minkowski\_conf\_wave\_\_amplitude ($a$)
@@ -444,6 +584,7 @@ These control $\Psi$ in the following form:
  \Psi=a\sin\left(\frac{2\pi}{l}D\right)+1
 \end{equation}
 Here $D$ is x, y or z according to d of 0, 1 or 2.
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 \section{Black Hole Spacetimes}
@@ -752,6 +893,10 @@ the mass $m_i = \verb|multi_BH__mass|\,i$ and the $x$, $y$, and $z$ positions
 $x_i = \verb|multi_BH__x|\,i$, $y_i = \verb|multi_BH__y|\,i$,
 and $z_i = \verb|multi_BH__z|\,i$ respectively.
 
+Note that this thorn does {\bf not} set $T_{\mu\nu}$.
+{\bf FIXME: does treating this metric as vacuum still give a solution
+to the Einstein equations?}
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 \subsection{Alvi post-Newtonian 2BH spacetime (not fully implemented yet)}
@@ -1098,6 +1243,19 @@ spacetimes, see gr-qc/0110031.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
+\subsection{Gowdy Spacetime}
+
+\verb|Exact::exact_model = "Gowdy"| specifies a Gowdy spacetime,
+which gives a polarized wave in an expanding universe.  See
+K.~New, K.~Watt, C.~W.~Misner, and J.~Centrella,
+``Stable 3-level leapfrog integration in numerical relativity'',
+PRD 58, 064022.
+
+There is only a single parameter, the wave amplitude
+\verb|Gowdy_wave__amplitude|.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
 \subsection{Milne Spacetime for Pre-Big-Bang Cosmology}
 
 \verb|Exact::exact_model = "Milne"| specifies a Milne spacetime,
@@ -1235,8 +1393,9 @@ spherical symmetry of the metric.
 The original code, including the boost-rotation symmetric metric
 and the slice evolver, was written by Carsten Gundlach and Miguel Alcubierre.
 Many different people have contributed exact solutions.
-Mitica Vulcanov wrote the Schwarzschild/Lemaitre solution and most
-(all?) of the cosmological solutions.
+The Schwarzschild/Lemaitre solution
+and most (all?) of the cosmological solutions
+were written by Mitica Vulcanov.
 The Minkowski/gauge wave model was written by Michael Koppitz.
 In May-June 2002 Jonathan Thornburg cleaned up a lot of the code,
 systematized the spacetime/coordinate and parameter names, and
@@ -1246,8 +1405,10 @@ code works.)
 The description of the Kastor-Traschen maximally charged multi-BH
 model is adapted from the file \verb|KTsol.tex| in this same directory,
 by Hisa-aki Shinkai.
+The Gowdy model was written by Denis Pollney.
 The \verb|ADMBase::evolution_method = "exact"| code was written
 by Peter Diener.
+The ``boost any vacuum solution'' code was written by Jonathan Thornburg.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
diff --git a/doc/how_to_add_a_new_model b/doc/how_to_add_a_new_model
index f2ac415..235feb5 100644
--- a/doc/how_to_add_a_new_model
+++ b/doc/how_to_add_a_new_model
@@ -1,7 +1,7 @@
 ************************************************
 ***** How to Add a New Model to this Thorn *****
 ************************************************
-$Header: /usr/local/svn/cvs-repositories/numrelcvs/AEIThorns/Exact/doc/how_to_add_a_new_model,v 1.4 2003-01-28 15:04:14 knarf Exp $
+$Header: /usr/local/svn/cvs-repositories/numrelcvs/AEIThorns/Exact/doc/how_to_add_a_new_model,v 1.5 2003-05-23 16:35:44 jthorn Exp $
 
 A general note:  Please keep the sections for various models in the
 same order in all the files.  This makes it _much_ easier for people
@@ -22,6 +22,11 @@ Then you need to modify...
 	gr-qc and/or well-known books.  Please also explain the physics
 	meanings of all the parameters -- users should *not* have to look
 	at your source code to figure out what a given parameter means!
+  README
+	Add a line or two giving the copyright status of your new code.
+	You can either put this in one of the existing licensing sections,
+	or create a new licensing section and add your copyright information
+	there.
   param.ccl:
 	Add the new model's character-string name as another possible value
 	for the exact_model parameter.
@@ -48,10 +53,14 @@ Then you need to modify...
 	It's probably easiest to start with a copy of an existing file and
 	modify it to compute your new metric -- that will help you get all
 	the "boilerplate" code right.
-  One additional information about the conformal factor which is passed
-  to the function: It is preset to 1.0 or 0.0 according to the fact if
-  it is wanted or not. If you want to have a physical metric, just do not
-  change it.
+	Please put a comment at the top of the file giving your name,
+	a copyright line, and the licensing status of the file (GPL, LGPL,
+	GPL-with-the-usual-Cactus-exemption-for-linking-with-non-GPL-thorns,
+	top-secret-you-can-look-at-it-but-then-we-have-to-shoot-you, whatever).
+	One additional information about the conformal factor which is passed
+	to the function: It is preset to 1.0 or 0.0 according to the fact if
+	it is wanted or not. If you want to have a physical metric, just do not
+	change it.
   src/metrics/make.code.defn:
 	Add the new file name to the list of files to be compiled.