! ---------------
! Example program
! Save attribute
! ---------------
program test
  implicit none
  integer, parameter:: n=3
  integer:: i
  real(kind(1.d0)):: A(n)
  do 
     do i = 1, n
        call random_number(A(i))
     end do
     call collect(A,n)
  end do
end program test
! ---------------------------------
! collect the average of 3D vectors 
! ---------------------------------
subroutine collect(vect,n)
   implicit none
  integer, intent(in):: n
   real(kind(1.d0)), intent(in)::vect(n)
   real(kind(1.d0)), allocatable, save, dimension(:):: vsum
   integer, save:: count=0
   if(count==0) allocate(vsum(n))
   vsum = vsum + vect
   count = count + 1
   if(count> 100000000) stop '100000000 done'
   if(mod(count,100000)==0) write(*,'("count=",i0," average=",3(1x,f0.8))')  count,vsum/count
end subroutine collect