MoL: add Multirate capabilities. This add three new multirate RK schemes to MoL.

Flags indicate whether it is time to execute slow RHS computation.
For instance, in the RK4-RK2 scheme, there are 4 substeps in total, but the RK2 RHS are only evaluated in the very first and in the very last step of the four substeps.

From: Christian Reisswig, minor changes by Roland Haas



git-svn-id: http://svn.cactuscode.org/arrangements/CactusNumerical/MoL/trunk@175 578cdeb0-5ea1-4b81-8215-5a3b8777ee0b

1 files changed, 27 insertions, 0 deletions

diff --git a/interface.ccl b/interface.ccl
index fa72e0c..d2d14f9 100644
--- a/interface.ccl
+++ b/interface.ccl
@@ -34,14 +34,21 @@ USES FUNCTION EnableProlongating
 
 CCTK_INT FUNCTION MoLRegisterEvolved(CCTK_INT IN EvolvedIndex, \
                                      CCTK_INT IN RHSIndex)
+CCTK_INT FUNCTION MoLRegisterEvolvedSlow(CCTK_INT IN EvolvedIndex, \
+                                         CCTK_INT IN RHSIndexSlow)
+
 CCTK_INT FUNCTION MoLRegisterConstrained(CCTK_INT IN ConstrainedIndex)
 CCTK_INT FUNCTION MoLRegisterSaveAndRestore(CCTK_INT IN SandRIndex)
 CCTK_INT FUNCTION MoLRegisterEvolvedGroup(CCTK_INT IN EvolvedIndex, \
                                           CCTK_INT IN RHSIndex)
+CCTK_INT FUNCTION MoLRegisterEvolvedGroupSlow(CCTK_INT IN EvolvedIndex, \
+                                              CCTK_INT IN RHSIndexSlow)
 CCTK_INT FUNCTION MoLRegisterConstrainedGroup(CCTK_INT IN ConstrainedIndex)
 CCTK_INT FUNCTION MoLRegisterSaveAndRestoreGroup(CCTK_INT IN SandRIndex)
 CCTK_INT FUNCTION MoLChangeToEvolved(CCTK_INT IN EvolvedIndex, \
                                      CCTK_INT IN RHSIndex)
+CCTK_INT FUNCTION MoLChangeToEvolvedSlow(CCTK_INT IN EvolvedIndex, \
+                                         CCTK_INT IN RHSIndexSlow)
 CCTK_INT FUNCTION MoLChangeToConstrained(CCTK_INT IN ConstrainedIndex)
 CCTK_INT FUNCTION MoLChangeToSaveAndRestore(CCTK_INT IN SandRIndex)
 CCTK_INT FUNCTION MoLChangeToNone(CCTK_INT IN RemoveIndex)
@@ -49,17 +56,21 @@ CCTK_INT FUNCTION MoLQueryEvolvedRHS(CCTK_INT IN EvolvedIndex)
 CCTK_INT FUNCTION MoLNumIntegratorSubsteps()
 
 PROVIDES FUNCTION MoLRegisterEvolved WITH MoL_RegisterEvolved LANGUAGE C
+PROVIDES FUNCTION MoLRegisterEvolvedSlow WITH MoL_RegisterEvolvedSlow LANGUAGE C
 PROVIDES FUNCTION MoLRegisterConstrained WITH MoL_RegisterConstrained \
                   LANGUAGE C
 PROVIDES FUNCTION MoLRegisterSaveAndRestore WITH MoL_RegisterSaveAndRestore \
                   LANGUAGE C
 PROVIDES FUNCTION MoLRegisterEvolvedGroup WITH MoL_RegisterEvolvedGroup \
                   LANGUAGE C
+PROVIDES FUNCTION MoLRegisterEvolvedGroupSlow WITH MoL_RegisterEvolvedGroupSlow \
+                  LANGUAGE C
 PROVIDES FUNCTION MoLRegisterConstrainedGroup WITH \
                   MoL_RegisterConstrainedGroup LANGUAGE C
 PROVIDES FUNCTION MoLRegisterSaveAndRestoreGroup WITH \
                   MoL_RegisterSaveAndRestoreGroup LANGUAGE C
 PROVIDES FUNCTION MoLChangeToEvolved WITH MoL_ChangeToEvolved LANGUAGE C
+PROVIDES FUNCTION MoLChangeToEvolvedSlow WITH MoL_ChangeToEvolvedSlow LANGUAGE C
 PROVIDES FUNCTION MoLChangeToConstrained WITH MoL_ChangeToConstrained \
                   LANGUAGE C
 PROVIDES FUNCTION MoLChangeToSaveAndRestore WITH MoL_ChangeToSaveAndRestore \
@@ -226,6 +237,17 @@ CCTK_INT MoL_Counters \
 {
   MoL_Intermediate_Step
   MoL_Stepsize_Bad
+  
+  # A flag indicating whether it is time for slow RHS evaluation. 
+  # Oustide the MoL loop, it is guaranteed to be 1.
+  # It is only zero for certain MoL substeps when multirate methods are used.
+  MoL_SlowStep
+  
+  # A flag indicating whether it is time for slow post step computations (e.g. applying BCs)
+  # Oustide the MoL loop, it is guaranteed to be 1.
+  # It is only zero for certain MoL substeps when multirate methods are used.
+  MoL_SlowPostStep
+  
 } "The counter for the time integration method"
 
 CCTK_REAL MoL_Original_Time \
@@ -241,6 +263,11 @@ CCTK_REAL ScratchSpace[MoL_Num_Evolved_Vars*MoL_Num_Scratch_Levels] \
             Timelevels = 1 \
             TAGS       = 'Prolongation="None" Checkpoint="no"'
 
+CCTK_REAL ScratchSpaceSlow[MoL_Num_Evolved_Vars_Slow*MoL_Num_Scratch_Levels] \
+            TYPE       = GF \
+            Timelevels = 1 \
+            TAGS       = 'Prolongation="None" Checkpoint="no"'
+
 CCTK_REAL SandRScratchSpace[MoL_Num_SaveAndRestore_Vars] \
             TYPE       = GF \
             Timelevels = 1 \