Hello,
I have written an MPI code to find acceleration (a = F/m) of a system of
particles. I would like to know how to perform MPI_GATHER of all the output
data at the root process and print the whole array (in the present case,
f(1:n) ) and reuse it for some other purpose in the serial part of the same
code. Please check the program given below and give me a solution.
program g
use mpi
implicit none
real(kind(1d0)),allocatable,dimension(:)::a, f
real(kind(1d0))::m
integer::i, n, true, ierr, np, irank, istart, iend, var, nprocs
nprocs= 4 !no: of processors used
n = 100 !no: of array elements
m = 12.0d0 !mass of the moving particle
var = n / nprocs !no: of array elements per process
allocate(a(n), f(n), stat=true)
if(true.ne.0) print*,'mem err'
call mpi_init(ierr)
call mpi_comm_size(mpi_comm_world, np, ierr)
call mpi_comm_rank(mpi_comm_world, irank, ierr)
istart= irank * var + 1
iend = (irank + 1) * var
do i= istart, iend
f(i) = dble(i) !the magnitude of force is taken
as continuous (real) numbers !!
a(i) = f(i) / m
end do
if(irank.eq.0) then !root process
do i=1,n
print*,i,a(i) !here, all the root elements are
printed correctly and the other elements as zeroes
end do
end if
call mpi_finalize(ierr)
end
Thanks in Advance
arun
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