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/*@@
@file RK4-RK2.c
@date 2012-03-25
@author Christian Reisswig
@desc
A routine to perform homegrown RK4RK2 evolution. Mostly copied from
genericRK.c
@enddesc
@version $Header$
@@*/
#include "cctk.h"
#include "cctk_Arguments.h"
#include "cctk_Parameters.h"
#include <stdio.h>
#include "ExternalVariables.h"
/* #define MOLDEBUG */
/*@@
@routine MoL_RK4_RK2_Add
@date
@author
@desc
Performs a single step of a RK4_RK2 type time
integration.
@enddesc
@calls
@calledby
@history
@endhistory
@@*/
void MoL_RK4_RK2_Add(CCTK_ARGUMENTS)
{
DECLARE_CCTK_ARGUMENTS;
DECLARE_CCTK_PARAMETERS;
#ifdef MOLDOESCOMPLEX
CCTK_WARN(CCTK_WARN_ABORT, "not implemented");
#endif
static int scratchspace_firstindex = -1;
static int scratchspace_firstindex_slow = -1;
if (scratchspace_firstindex < 0) {
scratchspace_firstindex = CCTK_FirstVarIndex("MOL::SCRATCHSPACE");
scratchspace_firstindex_slow = CCTK_FirstVarIndex("MOL::SCRATCHSPACESLOW");
}
int const step = MoL_Intermediate_Steps - *MoL_Intermediate_Step;
int totalsize = 1;
for (int d=0; d<cctk_dim; ++d) totalsize *= cctk_lsh[d];
CCTK_REAL const dt = *Original_Delta_Time / cctkGH->cctk_timefac;
int const allvar1 = MoLNumEvolvedVariables + MoLNumEvolvedVariablesSlow;
#pragma omp parallel for schedule(dynamic)
for (int var1=0; var1<allvar1; ++var1) {
if (var1 < MoLNumEvolvedVariables) {
/* a fast variable */
int const var = var1;
CCTK_REAL *restrict const UpdateVar =
CCTK_VarDataPtrI(cctkGH, 0, EvolvedVariableIndex[var]);
CCTK_REAL const *restrict const OldVar =
CCTK_VarDataPtrI(cctkGH, 1, EvolvedVariableIndex[var]);
CCTK_REAL const *restrict const RHSVar =
CCTK_VarDataPtrI(cctkGH, 0, RHSVariableIndex[var]);
#define SCRATCHINDEX(step) \
(scratchspace_firstindex + var + MoLNumEvolvedVariables * (step))
CCTK_REAL *restrict const ScratchVar =
CCTK_VarDataPtrI(cctkGH, 0, SCRATCHINDEX(0));
switch (step) {
case 0:
for (int i=0; i<totalsize; ++i) {
CCTK_REAL const scaled_rhs = dt * RHSVar[i];
ScratchVar[i] = OldVar[i] + 1.0/3.0 * scaled_rhs;
UpdateVar[i] = OldVar[i] + 0.5 * scaled_rhs;
}
break;
case 1:
for (int i=0; i<totalsize; ++i) {
CCTK_REAL const scaled_rhs = dt * RHSVar[i];
ScratchVar[i] += 1.0/6.0 * scaled_rhs;
UpdateVar[i] = OldVar[i] + 0.5 * scaled_rhs;
}
break;
case 2:
for (int i=0; i<totalsize; ++i) {
CCTK_REAL const scaled_rhs = dt * RHSVar[i];
ScratchVar[i] += 1.0/6.0 * scaled_rhs;
UpdateVar[i] = OldVar[i] + scaled_rhs;
}
break;
case 3:
for (int i=0; i<totalsize; ++i) {
CCTK_REAL const scaled_rhs = dt * RHSVar[i];
/* ScratchVar contains OldVar */
UpdateVar[i] = ScratchVar[i] + 1.0/3.0 * scaled_rhs;
}
break;
default:
assert(0);
}
#undef SCRATCHINDEX
} else {
/* a slow variable */
int const var = var1 - MoLNumEvolvedVariables;
CCTK_REAL *restrict const UpdateVar =
CCTK_VarDataPtrI(cctkGH, 0, EvolvedVariableIndexSlow[var]);
CCTK_REAL const *restrict const OldVar =
CCTK_VarDataPtrI(cctkGH, 1, EvolvedVariableIndexSlow[var]);
CCTK_REAL const *restrict const RHSVar =
CCTK_VarDataPtrI(cctkGH, 0, RHSVariableIndexSlow[var]);
#define SCRATCHINDEX(step) \
(scratchspace_firstindex_slow + var + MoLNumEvolvedVariablesSlow * (step))
CCTK_REAL *restrict const ScratchVar =
CCTK_VarDataPtrI(cctkGH, 0, SCRATCHINDEX(0));
switch (step) {
case 0:
for (int i=0; i<totalsize; ++i) {
CCTK_REAL const scaled_rhs = dt * RHSVar[i];
CCTK_REAL const scratchval = OldVar[i] + scaled_rhs;
ScratchVar[i] = scratchval;
UpdateVar[i] = scratchval;
}
break;
case 1:
case 2:
for (int i=0; i<totalsize; ++i) {
/* This is the same value as for the previous MoL step.
However, MoL_PostStep may have modified it (e.g. enforced
a constraint), so we need to recreate the original value
here for consistency. */
/* ScratchVar contains OldVar */
UpdateVar[i] = ScratchVar[i];
}
break;
case 3:
for (int i=0; i<totalsize; ++i) {
CCTK_REAL const scaled_rhs = dt * RHSVar[i];
/* ScratchVar contains OldVar */
UpdateVar[i] =
0.5 * OldVar[i] + 0.5 * ScratchVar[i] + 0.5 * scaled_rhs;
}
break;
default:
assert(0);
}
#undef SCRATCHINDEX
} /* if fast or slow */
} /* for var */
}
|
