def window_bartlett(N):
    """Bartlett window (wrapping of numpy.bartlett) also known as Fejer

    :param int N: window length

    The Bartlett window is defined as

    .. math:: w(n) = \\frac{2}{N-1} \\left(
              \\frac{N-1}{2} - \\left|n - \\frac{N-1}{2}\\right|
              \\right)

    .. plot::
        :width: 80%
        :include-source:

        from spectrum import window_visu
        window_visu(64, 'bartlett')

    .. seealso:: numpy.bartlett, :func:`create_window`, :class:`Window`.
    """
    from numpy import bartlett
    return bartlett(N)
