MoL Update

New integrator Euler. This is an explicit, first-order method, mostly
useful for debugging.

New integrators AB (Adams-Bashforth) with various orders. These are
explicit integrators using several past timelevels to provide
higher-order integration with a single RHS evaluation each.

Introduce LinearCombination, a generic routine to calculate linear
combinations of grid functions. This simplifies existing code, and can
be overloaded if MoL should run on a device (e.g. with OpenCL).

Replace cctk_lsh with cctk_ash where necessary.


git-svn-id: http://svn.cactuscode.org/arrangements/CactusNumerical/MoL/trunk@190 578cdeb0-5ea1-4b81-8215-5a3b8777ee0b

1 files changed, 116 insertions, 0 deletions

diff --git a/src/Euler.c b/src/Euler.c
new file mode 100644
index 0000000..0033cd1
--- /dev/null
+++ b/src/Euler.c
@@ -0,0 +1,116 @@
+ /*@@
+   @file      Euler.c
+   @date      2012-12-05
+   @author    Erik Schnetter
+   @desc 
+   An explicit Euler time integrator. This method is unstable in most
+   cases, but is sometimes useful for debugging.
+   @enddesc 
+   @version   $Header$
+ @@*/
+
+#include "cctk.h"
+#include "cctk_Arguments.h"
+#include "cctk_Parameters.h"
+
+#include "ExternalVariables.h"
+#include "Operators.h"
+
+static const char *rcsid = "$Header$";
+
+CCTK_FILEVERSION(CactusBase_MoL_Euler_c);
+
+/********************************************************************
+ *********************     Local Data Types   ***********************
+ ********************************************************************/
+
+/********************************************************************
+ ********************* Local Routine Prototypes *********************
+ ********************************************************************/
+
+/********************************************************************
+ ***************** Scheduled Routine Prototypes *********************
+ ********************************************************************/
+
+void MoL_EulerAdd(CCTK_ARGUMENTS);
+
+/********************************************************************
+ ********************* Other Routine Prototypes *********************
+ ********************************************************************/
+
+/********************************************************************
+ *********************     Local Data   *****************************
+ ********************************************************************/
+
+/********************************************************************
+ *********************     External Routines   **********************
+ ********************************************************************/
+
+ /*@@
+   @routine    MoL_EulerAdd
+   @date       2012-12-05
+   @author     Erik Schnetter
+   @desc 
+   Performs first order Euler time integration.
+   @enddesc 
+   @calls     
+   @calledby   
+   @history 
+ 
+   @endhistory 
+
+@@*/
+
+void MoL_EulerAdd(CCTK_ARGUMENTS)
+{
+  DECLARE_CCTK_ARGUMENTS;
+  DECLARE_CCTK_PARAMETERS;
+  
+  int totalsize = 1;
+  for (int arraydim = 0; arraydim < cctk_dim; arraydim++)
+  {
+    totalsize *= cctk_ash[arraydim];
+  }
+  
+  switch (*MoL_Intermediate_Step)
+  {
+  case 1:
+    {
+      for (int var = 0; var < MoLNumEvolvedVariables; var++)
+      {
+        int const nsrcs = 2;
+        CCTK_INT const srcs[] =
+          {EvolvedVariableIndex[var], RHSVariableIndex[var]};
+        CCTK_INT const tls[] = {1, 0};
+        CCTK_REAL const facts[] = {1.0, CCTK_DELTA_TIME};
+        MoL_LinearCombination(cctkGH,
+                              EvolvedVariableIndex[var], 0.0,
+                              srcs, tls, facts, nsrcs);
+      }
+      
+      for (int var = 0; var < MoLNumEvolvedArrayVariables; var++)
+      {
+        int const nsrcs = 2;
+        CCTK_INT const srcs[] =
+          {EvolvedArrayVariableIndex[var], RHSArrayVariableIndex[var]};
+        CCTK_INT const tls[] = {1, 0};
+        CCTK_REAL const facts[] = {1.0, CCTK_DELTA_TIME};
+        MoL_LinearCombination(cctkGH,
+                              EvolvedArrayVariableIndex[var], 0.0,
+                              srcs, tls, facts, nsrcs);
+      }
+      
+      break;
+    }
+  default:
+    {
+      CCTK_WARN(CCTK_WARN_ABORT,
+                "Euler expects MoL_Intermediate_Step to be in [1,1]. "
+                "This should be caught at ParamCheck - bug Ian!");
+    }
+  }
+}
+
+/********************************************************************
+ *********************     Local Routines   *************************
+ ********************************************************************/