program main

    implicit none

    integer :: n
    double precision, allocatable :: xh(:), xl(:)
    integer :: incx
    double precision :: dh, dl

    n = 2000
    incx = 1

    allocate(xh(1+(n-1)*abs(incx)))
    allocate(xl(1+(n-1)*abs(incx)))

    call random_number(xh)
    xl = 0d0

    call ddnrm2(n, xh, xl, incx, dh, dl)

    print *, "dh =", dh
    print *, "dl =", dl

end program