/* Function that creates a dataset for testing 0 (spherical octant)
1 (uniform cude) */
void create_dataset(float *X, int N, int dist){
switch(dist){
case 0:
cube(X, N);
break;
case 1:
plummer(X, N);
break;
default:
plummer(X, N);
break;
break;
}
}
nemo_main()
{
anisorad = getdparam("anisorad");
mcutoff = getdparam("mcutoff");
ntab = MXTB;
plummer();
writemodel(getparam("out"));
}
/**
* main program
*/
int main (int argc, char** argv)
{
/* hold positions, velocities, masses, and accelerations for the bodies */
double3 *x;
double3 *v;
double *m;
double3 *a;
/* temporary buffer given to leapfrog() so it can store the old acceleration
values there */
double3 *temp;
/* loop counter */
int i;
/* count the time steps done */
int k = 0;
/* base name for the output files */
char base[]="test1";
/* buffer to construct the whole output filename in */
char name[256];
/* handle for the output file */
FILE *file;
/* accumulated simulation time and time step size. These will be modified
when reading initial values from a file */
double t = 0, dt = 1E-3;
/* for measuring the elapsed time and calculating the MFLOP rate */
double start,stop,elapsed,flop;
/* number of bodies (read from commandline) */
int n;
/* number of time steps to do (read from commandline) */
int timesteps;
/* when to measure MFLOP rate and write output files: every mod time steps
(read from commandline) */
int mod;
int B;
/**
* parse commandline arguments
*/
if (argc!=5) {
printf("usage: nbody_vanilla <nbodies> <timesteps> <every> <Blocksize>\n");
return 1;
}
sscanf(argv[1],"%d",&n);
sscanf(argv[2],"%d",×teps);
sscanf(argv[3],"%d",&mod);
sscanf(argv[4],"%d",&B);
#if 0
/* get initial value from a data file */
file = fopen("plummer10000.vtk","r");
if (file==NULL) {
printf("could not open file --- aborting\n");
return 1;
}
/* peek into the file to find out the number of bodies */
n = get_vtk_numbodies(file);
rewind(file);
/* allocate memory accordingly */
x = calloc(n,sizeof(double3));
v = calloc(n,sizeof(double3));
m = calloc(n,sizeof(double));
/* read everything */
read_vtk_file_double(file,n,x,v,m,&t,&dt);
fclose(file);
printf("loaded %d bodies\n",n);
#else
/* get initial values from one of the generator functions */
x = calloc(n,sizeof(double3));
v = calloc(n,sizeof(double3));
m = calloc(n,sizeof(double));
plummer(n,17,x,v,m);
#endif
/**
* allocate and initialise the acceleration and the buffer for leapfrog
*/
a = calloc(n,sizeof(double3));
for (i=0; i<n; i++)
a[i][0] = a[i][1] = a[i][2] = 0.0;
acceleration(n,x,m,a,B);
temp = calloc(n,sizeof(double3));
/* write out the initial values */
sprintf(name,"%s_%06d.vtk",base,k/mod);
// printf("writing %s \n",name);
file = fopen(name,"w");
write_vtk_file_double(file,n,x,v,m,t,dt);
fclose(file);
/* start the time measurement */
start = get_time();
for (k=1; k<timesteps; k++) {
/* do one timestep and increment elapsed simulated time */
leapfrog(n,dt,x,v,m,a,temp);
t += dt;
if (k%mod==0) {
/* write statistics */
stop = get_time();
elapsed = stop-start;
/* 13*n*(n-1)+24*n+3 FLOP from leaprog(), 1 from the t+=dt above */
flop = mod*(13.0*n*(n-1.0)+24.0*n+4.0);
// printf("%g seconds for %g ops = %g MFLOPS\n",
printf("%g\n",flop/elapsed/1E6);
/* write output file */
sprintf(name,"%s_%06d.vtk",base,k/mod);
// printf("writing %s \n",name);
file = fopen(name,"w");
write_vtk_file_double(file,n,x,v,m,t,dt);
fclose(file);
/* restart the timer */
start = get_time();
}
}
/* Don't bother freeing the allocated buffers since the program is going to
end and the operating system will reclaim all of its memory anyway */
return 0;
}
