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Diffstat (limited to 'src/RK45.c')
| -rw-r--r-- | src/RK45.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/src/RK45.c b/src/RK45.c new file mode 100644 index 0000000..41a0462 --- /dev/null +++ b/src/RK45.c @@ -0,0 +1,236 @@ + /*@@ + @file RK45.c + @date Sun May 26 03:47:15 2002 + @author Ian Hawke + @desc + RK45 following Forsythe, Malcolm and Moler + (Computer Methods for Mathematical Computations). + @enddesc + @version $Header$ + @@*/ + +#include "cctk.h" +#include "cctk_Arguments.h" +#include "cctk_Parameters.h" + +#include "ExternalVariables.h" + +static const char *rcsid = "$Header$"; + +CCTK_FILEVERSION(CactusBase_MoL_RK45_c); + +/******************************************************************** + ********************* Local Data Types *********************** + ********************************************************************/ + +/******************************************************************** + ********************* Local Routine Prototypes ********************* + ********************************************************************/ + +/******************************************************************** + ***************** Scheduled Routine Prototypes ********************* + ********************************************************************/ + +void MoL_RK45Add(CCTK_ARGUMENTS); + +/******************************************************************** + ********************* Other Routine Prototypes ********************* + ********************************************************************/ + +/******************************************************************** + ********************* Local Data ***************************** + ********************************************************************/ + +/******************************************************************** + ********************* External Routines ********************** + ********************************************************************/ + + /*@@ + @routine MoL_RK45Add + @date Sun May 26 03:50:44 2002 + @author Ian Hawke + @desc + Performs a single step of a Runge-Kutta 45 type time + integration, storing the error estimate. + @enddesc + @calls + @calledby + @history + + @endhistory + +@@*/ + +void MoL_RK45Add(CCTK_ARGUMENTS) +{ + + DECLARE_CCTK_ARGUMENTS; + DECLARE_CCTK_PARAMETERS; + + cGroupDynamicData arraydata; + CCTK_INT groupindex, ierr; + CCTK_INT arraytotalsize, arraydim; + + CCTK_INT index, var, scratchstep, alphaindex, scratchindex; + CCTK_INT totalsize; + + CCTK_REAL *UpdateVar; + CCTK_REAL *RHSVar; + CCTK_REAL *ScratchVar; + CCTK_REAL *ErrorVar; + CCTK_REAL *OldVar; + + CCTK_INT arrayscratchlocation; + + CCTK_REAL beta, gamma, gamma_error; + + static const CCTK_REAL beta_array[5][5] = { + { 0.25, 0.0, 0.0, 0.0, 0.0 }, + { 0.09375, 0.28125, 0.0, 0.0, 0.0 }, + { 0.879380974055530268548020027310, -3.27719617660446062812926718252, 3.32089212562585343650432407829, 0.0, 0.0 }, + { 2.03240740740740740740740740741, -8.0, 7.17348927875243664717348927875, -0.205896686159844054580896686160, 0.0 }, + { -0.296296296296296296296296296296, 2.0, -1.38167641325536062378167641326, 0.452972709551656920077972709552, -0.275 } + }; + + static const CCTK_REAL gamma_array[6] = + { 0.118518518518518518518518518519, + 0.0, + 0.518986354775828460038986354776, + 0.506131490342016657806131490342, + -0.18, + 0.0363636363636363636363636363636 + }; + + static const CCTK_REAL gammastar_array[6] = + { 0.115740740740740740740740740741, + 0.0, + 0.548927875243664717348927875244, + 0.535331384015594541910331384016, + -0.2, + 0.0 + }; + + totalsize = 1; + for (arraydim = 0; arraydim < cctk_dim; arraydim++) + { + totalsize *= cctk_lsh[arraydim]; + } + + /* Real GFs */ + + /* First store (dt times) the rhs in the scratch array. */ + + for (var = 0; var < MoLNumEvolvedVariables; var++) + { + UpdateVar = (CCTK_REAL *)CCTK_VarDataPtrI(cctkGH, 0, + EvolvedVariableIndex[var]); + RHSVar = (CCTK_REAL *)CCTK_VarDataPtrI(cctkGH, 0, + RHSVariableIndex[var]); + ScratchVar = (CCTK_REAL*)CCTK_VarDataPtrI(cctkGH, 0, + CCTK_FirstVarIndex("MOL::SCRATCHSPACE") + + var + + MoL_Num_Evolved_Vars * + (MoL_Intermediate_Steps - + (*MoL_Intermediate_Step))); + for (index = 0; index < totalsize; index++) + { + ScratchVar[index] = (*Original_Delta_Time) / cctkGH->cctk_timefac * + RHSVar[index]; + } + } + + + 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, + CCTK_FirstVarIndex("MOL::SCRATCHSPACE") + + var + + MoL_Num_Evolved_Vars * + (MoL_Intermediate_Steps - + (*MoL_Intermediate_Step))); + ErrorVar = (CCTK_REAL*)CCTK_VarDataPtrI(cctkGH, 0, + CCTK_FirstVarIndex("MOL::ERRORESTIMATE") + + var); + + for (index = 0; index < totalsize; index++) + { + UpdateVar[index] = OldVar[index]; + ErrorVar[index] = 0; + } + + if (*MoL_Intermediate_Step - 1) + { + + for (scratchstep = 0; + scratchstep < MoL_Intermediate_Steps - (*MoL_Intermediate_Step) + 1; + scratchstep++) + { + + ScratchVar = (CCTK_REAL*)CCTK_VarDataPtrI(cctkGH, 0, + CCTK_FirstVarIndex("MOL::SCRATCHSPACE") + + var + + MoL_Num_Evolved_Vars * scratchstep); + + beta = beta_array[MoL_Intermediate_Steps - (*MoL_Intermediate_Step)][scratchstep]; + + if ( (beta > MoL_Tiny)||(beta < -MoL_Tiny) ) + { + for (index = 0; index < totalsize; index++) + { + UpdateVar[index] += beta * ScratchVar[index]; + } + } + + } + + } + else + { + for (scratchstep = 0; scratchstep < 6; scratchstep++) + { + + ScratchVar = (CCTK_REAL*)CCTK_VarDataPtrI(cctkGH, 0, + CCTK_FirstVarIndex("MOL::SCRATCHSPACE") + + var + + MoL_Num_Evolved_Vars * scratchstep); + + gamma = gamma_array[scratchstep]; + gamma_error = gamma - gammastar_array[scratchstep]; + + if ( (gamma > MoL_Tiny)||(gamma < -MoL_Tiny) ) + { + for (index = 0; index < totalsize; index++) + { + UpdateVar[index] += gamma * ScratchVar[index]; + ErrorVar[index] += gamma_error * ScratchVar[index]; + } + } + } + + } + + } + + /* Real arrays */ + + arrayscratchlocation = 0; + + for (var = 0; var < MoLNumEvolvedArrayVariables; var++) + { + + CCTK_WARN(0, "Ian has been too lazy to write the RK45 routine " + "out for array variables. Better send him an email..."); + + } + + return; +} + +/******************************************************************** + ********************* Local Routines ************************* + ********************************************************************/ + |