program check_sum
    implicit none
    integer, parameter :: nmol = 2, ndp = 2, npt = 50000
    real, dimension(npt+ndp,nmol) :: rd
    real, dimension(npt) :: y
    real :: c
    integer :: i, j

    call init_random_seed()
    call random_number(c)
    call random_number(rd)

    do i=1, npt
        y(i) = c*sum(rd(i+ndp,1:nmol))
    end do

    print *, y(10:15)

    y = 0d0
    do j=1,nmol
        do i=1, npt
            y(i) = y(i) + c*rd(i+ndp,j)
        end do
    end do

    print *, y(10:15)
contains
    subroutine init_random_seed()
        integer :: i, n, clock
        integer, dimension(:), allocatable :: seed

        call random_seed(size = n)
        allocate(seed(n))

        call system_clock(count=clock)

        seed = clock + 37 * (/ (i-1, i=1, n) /)
        call random_seed(put = seed)

        deallocate(seed)
    end subroutine init_random_seed
end program check_sum