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/*@@
@file Courant.c
@date September 4 1999
@author Gabrielle Allen
@desc
Specification of timestep using Courant condition
@enddesc
@@*/
#include <malloc.h>
#include <math.h>
#include "cctk.h"
#include "cctk_arguments.h"
#include "cctk_parameters.h"
void Time_Courant(CCTK_CARGUMENTS)
{
DECLARE_CCTK_PARAMETERS
DECLARE_CCTK_CARGUMENTS
CCTK_REAL min_spacing;
CCTK_REAL courant_speed;
char *message;
int min_handle,ierr;
/* Get the handle for the MINIMUM operation */
/*$ierr = CCTK_ReductionArrayHandle("minimum");$*/
/* Calculate the minimum grid spacing */
if (cctk_dim>=1)
{
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");
}
/* do the global minimum on local min_spacing to tmp and reassign that
to min_spacing */
/*$printf("Courant1: %d \n",min_spacing);
ierr = CCTK_ReduceLocalScalar(GH,-1,min_handle,min_spacing, tmp, CCTK_VAR_REAL);
printf("Courant2: %d \n",min_spacing,tmp);
min_spacing = tmp;
printf("Courant3: %d \n",min_spacing,tmp);$*/
/* Calculate the courant timestep */
courant_speed = *wave_speed;
*courant_dt = courant_fac/courant_speed/sqrt((CCTK_REAL )cctk_dim);
/* Output timestep if required */
if (outcourant_every > 0 && cctk_iteration%outcourant_every == 0)
{
CCTK_OutputVarAsByMethod(cctkGH,"time::courant_dt","Scalar","courant");
}
/* Set the Cactus timestep */
if (! courant_outonly)
{
cctkGH->cctk_delta_time = *courant_dt;
message = (char *)malloc(1024*sizeof(char));
sprintf(message,"Time step set to %f",cctkGH->cctk_delta_time);
CCTK_INFO(message);
free(message);
}
else
{
cctkGH->cctk_delta_time = dtfac*min_spacing/courant_wave_speed;
}
}
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