Added different bits of documentation, added code for a parameter

which wasn't being used (and changed its name but since it wasn't
implemented hopefully noone was using outtimestep_every). Removed two
scheduled routines which were not doing anything.

Fixes Cactus/1377, Cactus/1378, Cactus/1384, Cactus/1379.

Does not fix Cactus/1385 yet.


git-svn-id: http://svn.cactuscode.org/arrangements/CactusBase/Time/trunk@55 5633253d-7678-4964-a54d-f87795f8ee59

5 files changed, 60 insertions, 31 deletions

diff --git a/doc/documentation.tex b/doc/documentation.tex
index 69a6593..8e9e4b3 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -35,10 +35,14 @@ keyword parameter {\tt time::timestep\_method}.
 
 \begin{itemize}
 
-\item{} {\tt time::timestep\_method = ``given''} The timestep is fixed to the
+\item{} {\tt time::timestep\_method = "given"} 
+
+	The timestep is fixed to the
 	value of the parameter {\tt time::timestep}. 
 
-\item{} {\tt time::timestep\_method = ``courant\_static''} This is the default
+\item{} {\tt time::timestep\_method = "courant\_static"} 
+
+	This is the default
 	method, which calculates the timestep once at the start of the
 	simulation, based on a simple courant type condition using 
 	the spatial gridsizes and the parameter {\tt time::dtfac}.
@@ -48,25 +52,37 @@ $$
 	Note that it is up to the user to custom {\tt dtfac} to take
 	into account the dimension of the space being used, and the wave speed.
 
-\item{} {\tt time::timestep\_method = ``courant\_speed''} This choice implements a 
+\item{} {\tt time::timestep\_method = "courant\_speed"} 
+
+	This choice implements a 
 	dynamic courant type condition, the timestep being set before each
 	iteration using the spatial dimension of the grid, the spatial grid sizes, the 
 	parameter {\tt courant\_fac} and the grid variable {\tt courant\_wave\_speed}. 
 	The algorithm used is
 $$
-\Delta t = \mbox{\tt courant\_fac} * \mbox{min}(\Delta x^i)/\mbox{courant\_wave\_speed}/\sqrt(\mbox{dim})
+\Delta t = \mbox{\tt courant\_fac} * \mbox{min}(\Delta x^i)/\mbox{\tt courant\_wave\_speed}/\sqrt{\mbox dim}
 $$
 	For this algorithm to be successful, the variable {\tt courant\_wave\_speed}
-	must have been set by a thorn to the maximum wave speed on the grid.
+	must have been set by some thorn to the maximum propagation speed on the grid {\it before}
+	this thorn sets the timestep, that is {\tt AT POSTSTEP BEFORE Time\_Courant} (or earlier 
+	in the evolution loop). [Note: The name {\tt courant\_wave\_speed} was poorly 
+	chosen here, the required speed is the maximum propagation speed on 
+        the grid which may be larger than the maximum wave speed (for example
+        with a shock wave in hydrodynamics, also it is possible to have
+        propagation without waves as with a pure advection equation).
+
+\item{} {\tt time::timestep\_method = "courant\_time"} 
 
-\item{} {\tt time::timestep\_method = ``courant\_time''} This choice is similar to the
+	This choice is similar to the
 	method {\tt courant\_speed} above, in implementing a dynamic timestep.
 	However the timestep is chosen using
 $$
-\Delta t = \mbox{\tt courant\_fac} * \mbox{\tt courant\_min\_time}/\sqrt(\mbox{dim})
+\Delta t = \mbox{\tt courant\_fac} * \mbox{\tt courant\_min\_time}/\sqrt{\mbox dim}
 $$
-        where the grid variable {\tt courant\_min\_time} must be set by a thorn to
-	the minimum time for a wave to cross a gridzone.
+        where the grid variable {\tt courant\_min\_time} must be set by some thorn to
+	the minimum time for a wave to cross a gridzone {\it before}
+	this thorn sets the timestep, that is {\tt AT POSTSTEP BEFORE Time\_Courant} (or earlier 
+	in the evolution loop). 
 
 \end{itemize}
 
@@ -78,23 +94,26 @@ Note that for hyperbolic problems, the Courant condition gives a minimum
 requirement for stability, namely that the numerical domain of dependency
 must encompass the physical domain of dependency, or
 $$
-\Delta t \le \mbox{min}(\Delta x^i)/\mbox{wave speed}/\sqrt(\mbox{dim})
+\Delta t \le \mbox{min}(\Delta x^i)/\mbox{wave speed}/\sqrt{\mbox dim}
 $$
 
 \section{Examples}
 
+\noindent
 {\bf Fixed Value Timestep}
 
 {\tt
 \begin{verbatim}
-time::timestep_method = ``given''
+time::timestep_method = "given"
 time::timestep        = 0.1
 \end{verbatim}
 }
 
 
+\noindent
 {\bf Calculate Static Timestep Based on Grid Spacings}
 
+\noindent
 The following parameters set the timestep to be 0.25
 
 {\tt
@@ -102,7 +121,7 @@ The following parameters set the timestep to be 0.25
 grid::dx    = 0.5
 grid::dy    = 1.0
 grid::dz    = 1.0
-time::timestep_method = ``courant_static''
+time::timestep_method = "courant_static"
 time::dtfac = 0.5
 \end{verbatim}
 }
diff --git a/param.ccl b/param.ccl
index 2f9e89f..d9c1616 100644
--- a/param.ccl
+++ b/param.ccl
@@ -11,9 +11,9 @@ restricted:
 KEYWORD timestep_method "Method for calculating timestep"
 {
  "given"          :: "Use given timestep"
- "courant_static" :: "Courant condition at BASEGRID"
- "courant_speed"  :: "Courant condition at PRESTEP (using wavespeed)"
- "courant_time"   :: "Courant condition at PRESTEP (using min time)"
+ "courant_static" :: "Courant condition at BASEGRID (using dtfac)"
+ "courant_speed"  :: "Courant condition at POSTSTEP (using wavespeed and courant_fac)"
+ "courant_time"   :: "Courant condition at POSTSTEP (using min time and courant_fac)"
 } "courant_static"
 
 BOOLEAN timestep_outonly "Don't set a dynamic timestep, just output what it would be"
@@ -39,11 +39,11 @@ REAL courant_fac "The courant timestep condition dt = courant_fac*max(delta_spac
  *:0 :: "For negative timestep"
 } 0.9
 
-INT outtimestep_every "How often to output courant timestep"
+INT timestep_outevery "How often to output courant timestep"
 {
- 0:* :: "Zero means no output"
-} 0
+ 1:* :: "Zero means no output"
+} 1
 
-BOOLEAN verbose "Give information about timestep setting"
+BOOLEAN verbose "Give selective information about timestep setting"
 {
 } "no"
\ No newline at end of file
diff --git a/schedule.ccl b/schedule.ccl
index 927b5a1..12133ce 100644
--- a/schedule.ccl
+++ b/schedule.ccl
@@ -13,21 +13,28 @@ if (CCTK_Equals (timestep_method, "courant_static"))
   schedule Time_Simple at CCTK_BASEGRID after SpatialCoordinates
   {
     LANG: C
-  } "Set timestep based on Courant condition"
+  } "Set timestep based on Courant condition (courant_static)"
 }
-else if (CCTK_Equals (timestep_method, "courant_speed") ||
-         CCTK_Equals (timestep_method, "courant_time"))
+else if (CCTK_Equals (timestep_method, "courant_speed"))
 {
   schedule Time_Simple at CCTK_BASEGRID after SpatialCoordinates
   {
     LANG: C
-  } "Set timestep based on Courant condition"
+  } "Set timestep based on Courant condition (courant_speed)"
+
+   schedule Time_Courant at CCTK_POSTSTEP
+  {
+    LANG: C
+  } "Reset timestep each iteration"
+}
+else if (CCTK_Equals (timestep_method, "courant_time"))     
+
+{
+  schedule Time_Simple at CCTK_BASEGRID after SpatialCoordinates
+  {
+    LANG: C
+  } "Set timestep based on Courant condition (courant_time)"
 
-   schedule Time_Courant at CCTK_POSTINITIAL
-   {
-     LANG: C
-   } "Reset timestep each iteration"
- 
    schedule Time_Courant at CCTK_POSTSTEP
   {
     LANG: C
diff --git a/src/Courant.c b/src/Courant.c
index d40fb84..ba6587e 100644
--- a/src/Courant.c
+++ b/src/Courant.c
@@ -74,12 +74,15 @@ void Time_Courant(CCTK_ARGUMENTS)
     cctkGH->cctk_delta_time = *courant_dt;
     if (verbose)
     {
-      CCTK_VInfo(CCTK_THORNSTRING,"Time step set to %f",cctkGH->cctk_delta_time);
+      CCTK_VInfo(CCTK_THORNSTRING,"Time step set to %g",cctkGH->cctk_delta_time);
     }
   }
   else
   {
     cctkGH->cctk_delta_time = dtfac*min_spacing;
-    CCTK_VInfo(CCTK_THORNSTRING,"Courant timestep would be %f",*courant_dt);
+    if (cctkGH->cctk_iteration % timestep_outevery == 0)
+    {
+      CCTK_VInfo(CCTK_THORNSTRING,"Courant timestep would be %g",*courant_dt);
+    }
   }
 }
diff --git a/src/Simple.c b/src/Simple.c
index 39c049c..af22128 100644
--- a/src/Simple.c
+++ b/src/Simple.c
@@ -63,7 +63,7 @@ void Time_Simple(CCTK_ARGUMENTS)
   }
 
   CCTK_VInfo(CCTK_THORNSTRING,
-	     "Timestep set to %f (Simple Courant)",cctkGH->cctk_delta_time);
+	     "Timestep set to %g (courant_static)",cctkGH->cctk_delta_time);
 
 }