program sandbox
    implicit none
    real, dimension(2, 2) :: p
    real, dimension(:, :), allocatable :: q
    integer i, n

    n = 3
    allocate(q(2, 2*n))

    print *, "p"
    p = reshape([1, 3, 2, 4], shape(p))
    do i=1, 2
        print *, p(i, :)
    end do

    print *, "spread"
    q = reshape(spread(transpose(p), 2, n), [2, 2*n], order=[2, 1])
    do i=1, 2
        print *, q(i, :)
    end do
    deallocate(q)
end program sandbox