def maxzerodown(x):
    '''find all up zero crossings and return the index of the highest

    Not used anymore

    >>> np.random.seed(12345)
    >>> x = np.random.randn(8)
    >>> x
    array([-0.20470766,  0.47894334, -0.51943872, -0.5557303 ,  1.96578057,
            1.39340583,  0.09290788,  0.28174615])
    >>> maxzero(x)
    (4, array([1, 4]))


    no up-zero-crossing at end

    >>> np.random.seed(0)
    >>> x = np.random.randn(8)
    >>> x
    array([ 1.76405235,  0.40015721,  0.97873798,  2.2408932 ,  1.86755799,
           -0.97727788,  0.95008842, -0.15135721])
    >>> maxzero(x)
    (None, array([6]))
'''
    x = np.asarray(x)
    cond1 = x[:-1] > 0
    cond2 = x[1:] < 0
    #allzeros = np.nonzero(np.sign(x[:-1])*np.sign(x[1:]) <= 0)[0] + 1
    allzeros = np.nonzero((cond1 & cond2) | (x[1:]==0))[0] + 1
    if 0 <= x[-1]:
        maxz = max(allzeros)
    else:
        maxz = None
    return maxz, allzeros
dataset/ETHPy150Open statsmodels/statsmodels/statsmodels/sandbox/stats/multicomp.py/maxzerodown/swapped operands of `<=`