円周率計算 の履歴(No.1)

• 履歴一覧
• 差分 を表示
• 現在との差分 を表示
• ソース を表示
• 円周率計算 へ行く。
  • 1 (2018-11-27 (火) 08:50:50)

卒論

#include <stdio.h>
#include <math.h>
#include <mpi.h>

void main(int argc, char* argv[]){
 double PI25DT = 3.141592653589793238462643;
 double mypi, pi, h, sum, x, f, a;
 double t1, t2, t0, t_w;
 int n, myid, numprocs, i, rc;
 int ierr;
 
MPI_Status stat;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &myid);
MPI_Comm_size(MPI_COMM_WORLD, &numprocs);

 if(myid==0){
   printf("Enter the number of intervals \n");
   scanf("%d", &n);
   printf("n=%d \n", n);
            }

MPI_Barrier(MPI_COMM_WORLD);
t1=MPI_Wtime();

MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
   h = 1.0 / n;
   sum = 0.0;
 for(i=myid+1; i<=n; i+=numprocs){
     x = h * (i - 0.5);
     sum = sum + 4.0 / (1.0 + x*x);
                                 }

 mypi = h * sum;
MPI_Reduce(&mypi, &pi, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);

 if(myid == 0){
   printf("pi is approximately: %18.16lf Error is: %18.16lf \n", pi,fabs(pi-PI25DT));
              }

MPI_Barrier(MPI_COMM_WORLD);
t2 = MPI_Wtime();
t0= t2-t1;
MPI_Reduce(&t0, &t_w, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
   
 if(myid==0){   
   printf("execution time = : %8.4lf [sec.] \n", t_w);
            }
  rc= MPI_Finalize();
   
}