def alpha_conf_3obj_type1(x, t):
    """This function is used to calculate the alpha unction with time-varying
    conflicting objective (3-objective, type 1). Input are decision variable
    (x) and time (t).
    """
    k = int(abs(5.0 * (int(DELTA_STATE * int(t) / 5.0) % 2) - (DELTA_STATE * int(t) % 5)))
    alpha1 = fix_numerical_instability(np.cos(0.5 * x[0] * np.pi) * np.cos(0.5 * x[1] * np.pi))
    alpha2 = fix_numerical_instability(np.cos(0.5 * x[0] * np.pi) * np.sin(0.5 * x[1] * np.pi))
    alpha3 = fix_numerical_instability(np.sin(0.5 * x[0] * np.pi + 0.25 * (k / 5.0) * np.pi))
    return [alpha1, alpha2, alpha3]
This function is used to calculate the alpha unction with time-varying
    conflicting objective (3-objective, type 1). Input are decision variable
    (x) and time (t).
    
pymoo/vendor/gta.py