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, 9 insertions, 0 deletions

diff --git a/param.ccl b/param.ccl
index ba43b51..e82dd07 100644
--- a/param.ccl
+++ b/param.ccl
@@ -8,6 +8,12 @@ CCTK_INT MoL_Num_Evolved_Vars "The maximum number of variables to be evolved by
   0:*		:: "Anything non negative. Added to by other thorns."
 } 0
 
+CCTK_INT MoL_Num_Evolved_Vars_Slow "The maximum number of 'slow' variables to be evolved by MoL" ACCUMULATOR = (x+y)
+{
+  0:*		:: "Anything non negative. Added to by other thorns."
+} 0
+
+
 CCTK_INT MoL_Num_Constrained_Vars "The maximum number of constrained variables with timelevels that MoL needs to know about" ACCUMULATOR = (x+y)
 {
   0:*		:: "Anything non negative. Added to by other thorns."
@@ -92,6 +98,9 @@ KEYWORD ODE_Method "The ODE method use by MoL to do time integration"
   "RK45CK"      :: "RK45CK (Cash-Karp) with error estimation"
   "RK65"        :: "RK65 with error estimation"
   "RK87"        :: "RK87 with error estimation"
+  "RK2-MR-2:1"  :: "2nd order 2:1 multirate RK scheme based on RK2 due to Schlegel et al 2009"
+  "RK4-MR-2:1"  :: "3rd order 2:1 multirate RK scheme based on RK43 due to Schlegel et al 2009"
+  "RK4-RK2"     :: "RK4 as fast method and RK2 as slow method"
 } "ICN"
 
 KEYWORD Generic_Type "If using the generic method, which sort"