def METHOD_NAME(xx):
    """Ishigami function"""
    a = 7
    b = 0.1
    term1 = np.sin(xx[0])
    term2 = a * np.sin(xx[1])**2
    term3 = b * xx[2]**4 * np.sin(xx[0])
    return term1 + term2 + term3