int main (int argc, char *argv[])
{
double homepi, /* value of pi calculated by current task */
pisum, /* sum of tasks' pi values */
pi, /* average of pi after "darts" is thrown */
avepi; /* average pi value for all iterations */
int taskid, /* task ID - also used as seed number */
numtasks, /* number of tasks */
rc, /* return code */
i;
MPI_Status status;
setvbuf( stdout, NULL, _IONBF, 0 );
/* Obtain number of tasks and task ID */
MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD,&numtasks);
MPI_Comm_rank(MPI_COMM_WORLD,&taskid);
printf ("MPI task %d has started...\n", taskid);
/* Set seed for random number generator equal to task ID */
srandom (taskid);
avepi = 0;
for (i = 0; i < ROUNDS; i++) {
/* All tasks calculate pi using dartboard algorithm */
homepi = dboard(DARTS);
/* Use MPI_Reduce to sum values of homepi across all tasks
* Master will store the accumulated value in pisum
* - homepi is the send buffer
* - pisum is the receive buffer (used by the receiving task only)
* - the size of the message is sizeof(double)
* - MASTER is the task that will receive the result of the reduction
* operation
* - MPI_SUM is a pre-defined reduction function (double-precision
* floating-point vector addition). Must be declared extern.
* - MPI_COMM_WORLD is the group of tasks that will participate.
*/
printf ("MPI task %d pi %10.8f\n", taskid,homepi);
rc = MPI_Reduce(&homepi, &pisum, 1, MPI_DOUBLE, MPI_SUM,
MASTER, MPI_COMM_WORLD);
if (rc != MPI_SUCCESS)
printf("%d: failure on mpc_reduce\n", taskid);
/* Master computes average for this iteration and all iterations */
if (taskid == MASTER) {
pi = pisum/numtasks;
avepi = ((avepi * i) + pi)/(i + 1);
printf(" After %8d throws, average value of pi = %10.8f\n",
(DARTS * (i + 1)),avepi);
}
}
if (taskid == MASTER)
printf ("\nReal value of PI: 3.1415926535897 \n");
MPI_Finalize();
return 0;
}
int main(int argc, const char *argv[])
{
double homepi,
pisum,
pi,
avepi = 0.;
int taskid,
numtasks,
rc;
MPI_Init(&argc, (char***)&argv);
MPI_Comm_size(MPI_COMM_WORLD, &numtasks);
MPI_Comm_rank(MPI_COMM_WORLD, &taskid);
if (taskid == MASTER) {
printf("Parallel computing of pi (3.1415926535), using %d tasks.\n", numtasks);
}
printf("MPI task %d has started...\n", taskid);
srandom((unsigned int)time(NULL));
int i;
for (i = 0; i < ROUNDS; i++) {
homepi = dboard((int)(DARTS / numtasks));
rc = MPI_Reduce(&homepi, &pisum, 1, MPI_DOUBLE, MPI_SUM, MASTER, MPI_COMM_WORLD);
if (rc != MPI_SUCCESS) {
fprintf(stderr, "%d: failure on MPI_Reduce\n", taskid);
}
if (taskid == MASTER) {
pi = pisum / numtasks;
avepi = ((avepi * i) + pi) / (i + 1);
// printf(" After %.0Lf throws, average value of pi = %.10f\n", (long double)(DARTS * (i + 1)), avepi);
}
}
if (taskid == MASTER) {
printf("Parallel computing of pi 3.1415926535\n");
printf(" %.10f\n", avepi);
}
MPI_Finalize();
return (0);
}
int main(int argc, char **argv) {
double homepi;
char buf[BUFSIZ];
int DARTS;
double start, finish, elapsed;
printf ("\nnumber of DARTS: ");
if (fgets(buf, sizeof(buf), stdin) != NULL) { DARTS = atoi(buf); }
start = (double) clock() / CLOCKS_PER_SEC;
homepi = dboard(DARTS);
finish = (double) clock() / CLOCKS_PER_SEC;
elapsed = finish - start;
printf("\nFor %d darts, pi = %0.20f", DARTS, homepi);
printf("elapsed time = %.3f sec\n\n", elapsed);
}
int main (int argc, char *argv[])
{
double homepi, /* value of pi calculated by current task */
pi, /* average of pi after "darts" is thrown */
avepi, /* average pi value for all iterations */
pirecv, /* pi received from worker */
pisum; /* sum of workers pi values */
int taskid, /* task ID - also used as seed number */
numtasks, /* number of tasks */
source, /* source of incoming message */
mtype, /* message type */
rc, /* return code */
i, n;
MPI_Status status;
/* Obtain number of tasks and task ID */
MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD,&numtasks);
MPI_Comm_rank(MPI_COMM_WORLD,&taskid);
printf ("MPI task %d has started...\n", taskid);
/* Set seed for random number generator equal to task ID */
srandom (taskid);
avepi = 0;
for (i = 0; i < ROUNDS; i++) {
/* All tasks calculate pi using dartboard algorithm */
homepi = dboard(DARTS);
/* Workers send homepi to master */
/* - Message type will be set to the iteration count */
if (taskid != MASTER) {
mtype = i;
rc = MPI_Send(&homepi, 1, MPI_DOUBLE,
MASTER, mtype, MPI_COMM_WORLD);
if (rc != MPI_SUCCESS)
printf("%d: Send failure on round %d\n", taskid, mtype);
}
else
{
/* Master receives messages from all workers */
/* - Message type will be set to the iteration count */
/* - Message source will be set to the wildcard DONTCARE: */
/* a message can be received from any task, as long as the */
/* message types match */
/* - The return code will be checked, and a message displayed */
/* if a problem occurred */
mtype = i;
pisum = 0;
for (n = 1; n < numtasks; n++) {
rc = MPI_Recv(&pirecv, 1, MPI_DOUBLE, MPI_ANY_SOURCE,
mtype, MPI_COMM_WORLD, &status);
if (rc != MPI_SUCCESS)
printf("%d: Receive failure on round %d\n", taskid, mtype);
/* keep running total of pi */
pisum = pisum + pirecv;
}
/* Master calculates the average value of pi for this iteration */
pi = (pisum + homepi)/numtasks;
/* Master calculates the average value of pi over all iterations */
avepi = ((avepi * i) + pi)/(i + 1);
printf(" After %8d throws, average value of pi = %10.8f\n",
(DARTS * (i + 1)),avepi);
}
}
if (taskid == MASTER)
printf ("\nReal value of PI: 3.1415926535897 \n");
MPI_Finalize();
return 0;
}
