FORTRAN Example

• IMPLICIT DOUBLE PRECISION (A-H,O-Z)

• INCLUDE 'mpif.h'

• call MPI_INIT(ierr)

• call MPI_COMM_RANK(MPI_COMM_WORLD,myid,ierr)

• call MPI_COMM_SIZE(MPI_COMM_WORLD,np,ierr)

• print *, 'Process ', myid, ' of ', np

• n = 10000000

• call MPI_BCAST(n,1,MPI_INTEGER,0,MPI_COMM_WORLD,ierr)

• h = 1.0/n

• sum = 0

• do i = myid+1,n,np

• x = h * (i - 0.5)

• sum = sum + 4/(1+x**2)

• enddo

• call MPI_REDUCE(h*sum,pi,1,MPI_DOUBLE_PRECISION,

• | MPI_SUM,0,MPI_COMM_WORLD,ierr)

• if (myid.eq.0) print *,'pi=',pi,

• | ' err=',pi - 3.141592653589793238462643

• call MPI_FINALIZE(ierr)

• END

  • See Appendix C for a more complete example

Notes: