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/*@@
@file RK2.c
@date Sun May 26 04:13:45 2002
@author Ian Hawke
@desc
A specialized second order Runge-Kutta time integrator. This is
the integrator that Shu refers to as the optimal TVD second
order method (see reference in documentation). It is equivalent
to Heun's predictor-corrector method, or the MacCormack method.
@enddesc
@version $Header$
@@*/
#include "cctk.h"
#include "cctk_Arguments.h"
#include "cctk_Parameters.h"
#include "ExternalVariables.h"
static const char *rcsid = "$Header$";
CCTK_FILEVERSION(AlphaThorns_MoL_RK2_c);
/********************************************************************
********************* Local Data Types ***********************
********************************************************************/
/********************************************************************
********************* Local Routine Prototypes *********************
********************************************************************/
/********************************************************************
***************** Scheduled Routine Prototypes *********************
********************************************************************/
void MoL_RK2Add(CCTK_ARGUMENTS);
/********************************************************************
********************* Other Routine Prototypes *********************
********************************************************************/
/********************************************************************
********************* Local Data *****************************
********************************************************************/
/********************************************************************
********************* External Routines **********************
********************************************************************/
/*@@
@routine MoL_RK2Add
@date Sun May 26 04:17:23 2002
@author Ian Hawke
@desc
Performs second order Runge-Kutta time integration.
@enddesc
@calls
@calledby
@history
@endhistory
@@*/
void MoL_RK2Add(CCTK_ARGUMENTS)
{
DECLARE_CCTK_ARGUMENTS;
DECLARE_CCTK_PARAMETERS;
CCTK_INT index, var;
CCTK_INT totalsize;
CCTK_REAL *OldVar;
CCTK_REAL *UpdateVar;
CCTK_REAL *RHSVar;
/*
printf("Inside RK2.\nStep %d.\nRefinement %d.\nTimestep %g.\nSpacestep %g.\nTime %g\n",
MoL_Intermediate_Steps - *MoL_Intermediate_Step + 1,
*cctk_levfac,
cctk_delta_time,
CCTK_DELTA_SPACE(0),
cctk_time);
*/
totalsize = cctk_lsh[0] * cctk_lsh[1] * cctk_lsh[2];
switch (*MoL_Intermediate_Step)
{
case 2:
{
for (var = 0; var < MoLNumEvolvedVariables; var++)
{
UpdateVar = (CCTK_REAL*)CCTK_VarDataPtrI(cctkGH, 0,
EvolvedVariableIndex[var]);
RHSVar = (CCTK_REAL*)CCTK_VarDataPtrI(cctkGH, 0,
RHSVariableIndex[var]);
for (index = 0; index < totalsize; index++)
{
UpdateVar[index] += CCTK_DELTA_TIME * RHSVar[index];
}
}
break;
}
case 1:
{
for (var = 0; var < MoLNumEvolvedVariables; var++)
{
OldVar = (CCTK_REAL*)CCTK_VarDataPtrI(cctkGH, 1,
EvolvedVariableIndex[var]);
UpdateVar = (CCTK_REAL*)CCTK_VarDataPtrI(cctkGH, 0,
EvolvedVariableIndex[var]);
RHSVar = (CCTK_REAL*)CCTK_VarDataPtrI(cctkGH, 0,
RHSVariableIndex[var]);
for (index = 0; index < totalsize; index++)
{
UpdateVar[index] = 0.5 * (OldVar[index] + UpdateVar[index]) +
CCTK_DELTA_TIME * RHSVar[index];
}
}
break;
}
default:
{
CCTK_WARN(0, "RK2 expects MoL_Intermediate_Step to be in [1,2]. This should be caught at ParamCheck - bug Ian!");
break;
}
}
return;
}
/********************************************************************
********************* Local Routines *************************
********************************************************************/
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