You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
69 lines
1.5 KiB
69 lines
1.5 KiB
#include "mpi.h"
|
|
#include <stdio.h>
|
|
#include <math.h>
|
|
|
|
double f( double );
|
|
|
|
double f( double a)
|
|
{
|
|
return (4.0 / (1.0 + a*a));
|
|
}
|
|
|
|
int main( int argc, char *argv[] )
|
|
{
|
|
int done = 0, n, myid, numprocs, i;
|
|
double PI25DT = 3.141592653589793238462643;
|
|
double mypi, pi, h, sum, x;
|
|
double startwtime=0.0, endwtime;
|
|
int namelen;
|
|
char processor_name[MPI_MAX_PROCESSOR_NAME];
|
|
|
|
MPI_Init(&argc,&argv);
|
|
MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
|
|
MPI_Comm_rank(MPI_COMM_WORLD,&myid);
|
|
MPI_Get_processor_name(processor_name,&namelen);
|
|
|
|
fprintf(stderr,"Process %d on %s\n",
|
|
myid, processor_name);
|
|
|
|
while (!done)
|
|
{
|
|
if (myid == 0)
|
|
{
|
|
printf("Enter the number of intervals (0 quits):\n");
|
|
scanf("%d",&n);
|
|
|
|
startwtime = MPI_Wtime();
|
|
}
|
|
MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
|
|
if (n == 0)
|
|
done = 1;
|
|
else
|
|
{
|
|
h = 1.0 / (double) n;
|
|
sum = 0.0;
|
|
for (i = myid + 1; i <= n; i += numprocs)
|
|
{
|
|
x = h * ((double)i - 0.5);
|
|
sum += f(x);
|
|
}
|
|
mypi = h * sum;
|
|
|
|
MPI_Reduce(&mypi, &pi, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
|
|
|
|
if (myid == 0)
|
|
{
|
|
printf("pi is approximately %.16f, Error is %.16f\n",
|
|
pi, fabs(pi - PI25DT));
|
|
endwtime = MPI_Wtime();
|
|
printf("wall clock time = %f\n",
|
|
endwtime-startwtime);
|
|
}
|
|
}
|
|
}
|
|
MPI_Finalize();
|
|
}
|
|
|
|
|
|
|
|
|
|
|