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/*@@
@file Courant.c
@date September 4 1999
@author Gabrielle Allen
@desc
Specification of timestep using Courant condition
@enddesc
@version $Id$
@@*/
#include <stdlib.h>
#include <math.h>
#include "cctk.h"
#include "cctk_Arguments.h"
#include "cctk_Parameters.h"
static const char *rcsid = "$Header$";
CCTK_FILEVERSION(CactusBase_Time_Courant_c)
void Time_Courant(CCTK_ARGUMENTS);
void Time_Courant(CCTK_ARGUMENTS)
{
CCTK_REAL min_spacing;
DECLARE_CCTK_PARAMETERS
DECLARE_CCTK_ARGUMENTS
/* Calculate the minimum grid spacing */
min_spacing = cctk_delta_space[0];
if (cctk_dim>=2)
{
min_spacing = (min_spacing<cctk_delta_space[1] ?
min_spacing : cctk_delta_space[1]);
}
if (cctk_dim>=3)
{
min_spacing = (min_spacing<cctk_delta_space[2] ?
min_spacing : cctk_delta_space[2]);
}
if (cctk_dim>=4)
{
CCTK_WARN(0,"Time Step not defined for greater than 4 dimensions");
}
/* Calculate the courant timestep */
if (CCTK_Equals(timestep_method,"courant_time"))
{
*courant_dt = courant_fac*(*courant_min_time)/sqrt((double)cctk_dim);
}
else if (CCTK_Equals(timestep_method,"courant_speed"))
{
*courant_dt = courant_fac*min_spacing/
(*courant_wave_speed)/sqrt((double) cctk_dim);
}
if (CCTK_Equals(terminate, "time")||CCTK_Equals(terminate, "both"))
{
if (cctkGH->cctk_time + *courant_dt > cctk_final_time)
{
*courant_dt = (1 + 1.e-10) * (cctk_final_time - cctkGH->cctk_time);
}
}
/* Set the Cactus timestep */
if (!timestep_outonly)
{
cctkGH->cctk_delta_time = *courant_dt;
if (verbose)
{
CCTK_VInfo(CCTK_THORNSTRING,"Time step set to %g",CCTK_DELTA_TIME);
}
}
else
{
cctkGH->cctk_delta_time = dtfac*min_spacing;
if (cctkGH->cctk_iteration % timestep_outevery == 0)
{
CCTK_VInfo(CCTK_THORNSTRING,"Courant timestep would be %g",*courant_dt);
}
}
}
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