int main(int argc, char *argv[]) {
MPI_Init(&argc,&argv);
int myrank;
int nprocs;
MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
int n, iters, timestep;
double** s; // position in 3D space for each body
double** v; // velocity in 3D space for each body
double* m; // mass of each body
int size; // # of bodies stored on each proc.
// arguments: ./nBody r #n #iter #timestep
// or ./nBody g #n #iter #timestep
if (argc != 5) {
fprintf(stderr, "Usage: %s MODE BODIES ITERATIONS TIMESTEP\n", argv[0]);
fprintf(stderr, "\nMODE must be either r[ead] or g[enerate]\n");
exit(0);
}
n = atoi(argv[2]); // total number of bodies
size = n / nprocs; // number of bodies in this processor
iters = atoi(argv[3]);
timestep = atoi(argv[4]);
size = n / nprocs;
int i;
int j;
// position vectors for bodies in this processor
s = (double **)malloc(sizeof(double *) * size);
for (i = 0; i < size; i++) {
s[i] = (double*)malloc(sizeof(double) * 3);
for(j = 0; j < 3; j++) {
s[i][j] = 0;
}
}
// velocity vectors for bodies in this processor
v = (double **)malloc(sizeof(double *) * size);
for (i = 0; i < size; i++) {
v[i] = (double*)malloc(sizeof(double) * 3);
for(j = 0; j < 3; j++) {
v[i][j] = 0;
}
}
// mass values for bodies in this processor
m = (double *)malloc(sizeof(double) * size);
for(i = 0; i < size; i++) {
m[i] = 0;
}
if (strcmp(argv[1], "r") == 0) {
readnbody(s, v, m, n);
} else {
gennbody(s, v, m, n);
}
nbody(s, v, m, n, iters, timestep);
for (i = 0; i < size; i++) {
free(s[i]);
free(v[i]);
}
free(s);
free(v);
free(m);
MPI_Finalize();
return 0;
}
std::vector<vex::command_queue> queue(1, ctx.queue(0));
std::vector<double> X = random_vector<double>(n);
vex::vector<double> x(queue, X);
vex::vector<double> y(queue, n);
VEX_FUNCTION(double, nbody, (size_t, n)(size_t, j)(double*, x),
double sum = 0;
for(size_t i = 0; i < n; ++i)
if (i != j) sum += x[i];
return sum;
);
y = nbody(n, vex::element_index(), vex::raw_pointer(x));
check_sample(y, [&](size_t idx, double v) {
double sum = 0;
for(size_t i = 0; i < n; ++i)
if (i != idx) sum += X[i];
BOOST_CHECK_CLOSE(v, sum, 1e-8);
});
}
BOOST_AUTO_TEST_CASE(manual_stencil)
{
const size_t n = 1024;
std::vector<vex::command_queue> queue(1, ctx.queue(0));
