Small optimisation: substitute division by multiplication with the inverse.

git-svn-id: http://svn.cactuscode.org/arrangements/CactusNumerical/MoL/trunk@91 578cdeb0-5ea1-4b81-8215-5a3b8777ee0b

2 files changed, 7 insertions, 4 deletions

diff --git a/src/RK3.c b/src/RK3.c
index 1ecdcf5..cf21414 100644
--- a/src/RK3.c
+++ b/src/RK3.c
@@ -262,6 +262,8 @@ void MoL_RK3Add(CCTK_ARGUMENTS)
       }
     case 1:
       {
+        const CCTK_REAL one_third = 1.0 / 3.0;
+
         for (var = 0; var < MoLNumEvolvedVariables; var++)
         {
           OldVar = (CCTK_REAL*)CCTK_VarDataPtrI(cctkGH, 1,
@@ -273,7 +275,7 @@ void MoL_RK3Add(CCTK_ARGUMENTS)
           
           for (index = 0; index < totalsize; index++)
           {
-            UpdateVar[index] = (OldVar[index] + 2*UpdateVar[index])/3
+            UpdateVar[index] = (OldVar[index] + 2*UpdateVar[index]) * one_third
               + CCTK_DELTA_TIME * RHSVar[index];
           }
         }
@@ -305,7 +307,7 @@ void MoL_RK3Add(CCTK_ARGUMENTS)
           
           for (index = 0; index < arraytotalsize; index++)
           {
-            UpdateVar[index] = (OldVar[index] + 2*UpdateVar[index])/3
+            UpdateVar[index] = (OldVar[index] + 2*UpdateVar[index]) * one_third
               + CCTK_DELTA_TIME * RHSVar[index];
           }
         }
diff --git a/src/RK45.c b/src/RK45.c
index 41a0462..b2f6c88 100644
--- a/src/RK45.c
+++ b/src/RK45.c
@@ -122,6 +122,8 @@ void MoL_RK45Add(CCTK_ARGUMENTS)
 
   for (var = 0; var < MoLNumEvolvedVariables; var++)
   {
+    const CCTK_REAL tmp = (*Original_Delta_Time) / cctkGH->cctk_timefac;
+
     UpdateVar = (CCTK_REAL *)CCTK_VarDataPtrI(cctkGH, 0, 
                                               EvolvedVariableIndex[var]);
     RHSVar = (CCTK_REAL *)CCTK_VarDataPtrI(cctkGH, 0, 
@@ -134,8 +136,7 @@ void MoL_RK45Add(CCTK_ARGUMENTS)
                                                (*MoL_Intermediate_Step)));
     for (index = 0; index < totalsize; index++)
     {
-      ScratchVar[index] = (*Original_Delta_Time) / cctkGH->cctk_timefac *
-        RHSVar[index];
+      ScratchVar[index] = tmp * RHSVar[index];
     }
   }