def hill_func(x, a, b, c, d):
    """Hill function
    commonly used to fit MIC curves

    Args:
        x (numpy.array)
            Concentration vector (n, 1)
        a (float)
        b (float)
        c (float)
        d (float)

    Returns:
        y (float)
    """
    return a+(b-a)/(1+(x/c)**d)