def six_hump_camel_func(x):
    """
    Definition of the six-hump camel
    """
    x1 = x[0]
    x2 = x[1]
    term1 = (4-2.1*x1**2+(x1**4)/3) * x1**2;
    term2 = x1*x2;
    term3 = (-4+4*x2**2) * x2**2;

    return  term1 + term2 + term3