Previously there was no easy and documented way to generate an

entire exact spacetime (not just a t=0 slice).  (The "slice_evolver.tex"
stuff might may be able to do this, but it looks complicated. :( )

This change adds this feature (and removes it from the TODO):
just set    ADMBase::evolution_method = "exact"

Thanks to Peter Diener for implementing this!  (It turned out to
be unexpectedly easy: just re-schedule the appropriate setup routine
in CCTK_PRESTEP at each slice!)


git-svn-id: http://svn.einsteintoolkit.org/cactus/EinsteinInitialData/Exact/trunk@141 e296648e-0e4f-0410-bd07-d597d9acff87

2 files changed, 21 insertions, 19 deletions

diff --git a/doc/TODO b/doc/TODO
index 53be0e1..4475003 100644
--- a/doc/TODO
+++ b/doc/TODO
@@ -22,18 +22,6 @@ than 1 point.
 
 ----------------------------------------
 
-Peter Diener:
-There's no documented way to generate an entire exact spacetime
-(not just a t=0 slice).  The "slice_evolver.tex" stuff may be able
-to do this, but it looks complicated. :(  There ought to be a
-simple way of doing this!  (And it ought to be documented simply, too!)
-
---> Peter has come up with a small patch to the param.ccl and schedule.ccl
-    files which does this.  I (JT) need to document this and commit it
-    to CVS.
-
-----------------------------------------
-
 Every model should have .ge. 1 test case!  Right now most of the
 models have no test cases at all, and this makes it way too easy for
 bugs to creep in and go undetected for a long time.
diff --git a/doc/documentation.tex b/doc/documentation.tex
index bfa06f4..714719d 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -117,7 +117,7 @@
 
 % Add an abstract for this thorn's documentation
 \begin{abstract}
-This thorn sets up the $3+1$ ADM field variables for any of a number
+This thorn sets up the $3+1$ ADM variables for any of a number
 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
@@ -133,19 +133,31 @@ order to test gauge conditions without the need for an evolution code.
 
 \section{Introduction}
 
-This thorn sets up the ADM field variables for any of a number of
+This thorn sets up the ADM variables for any of a number of
 different spacetimes/coordinates (we call the combination of a
 spacetime and a coordinate system a \defn{model}), as specified by the
 \verb|Exact::exact_model| parameter.
 
-Optionally, 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 exact
-solution, in order to check on an evolution code, or in order to test
-gauge conditions without the need for an evolution code. This is
+By default, this thorn sets up the ADM variables on an initial
+slice only.  However, setting\\
+\verb|ADMBase::evolution_method = "exact"|
+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 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
+other thorn(s), 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.  This option is
 documented in the file \verb|slice_evolver.tex| in the \verb|doc/|
 directory.
 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\subsection{Models Supported}
+
 The following models are currently supported:%%%
 \footnote{%%%
 	 To add a new model, you have to modify a
@@ -1209,6 +1221,8 @@ 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 \verb|ADMBase::evolution_method = "exact"| code was written
+by Peter Diener.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%