subroutine dot_prod8(prod_8,f,g,n) include 'mpif.h' include "my_comm.h" real(8) prod_8 real(4) f(n),g(n) real(8) fg_8,sum_8 sum_8=0._8 if(n.gt.0) then do i=1,n fg_8=f(i)*g(i) sum_8=sum_8+fg_8 end do end if call mpi_allreduce(sum_8,prod_8,1,mpi_real8,mpi_sum,my_comm,ierr) return end