def METHOD_NAME(n=512, beta=800, mu=4.9, dur=0.012):
    r"""Design a hyperbolic secant adiabatic pulse.
    mu * beta becomes the amplitude of the frequency sweep
    Args:
        n (int): number of samples (should be a multiple of 4).
        beta (float): AM waveform parameter.
        mu (float): a constant, determines amplitude of frequency sweep.
        dur (float): pulse time (s).
    Returns:
        2-element tuple containing
        - **a** (*array*): AM waveform.
        - **om** (*array*): FM waveform (radians/s).
    References:
        Baum, J., Tycko, R. and Pines, A. (1985). 'Broadband and adiabatic
        inversion of a two-level system by phase-modulated pulses'.
        Phys. Rev. A., 32:3435-3447.
    """
    t = np.arange(-n // 2, n // 2) / n * dur
    a = np.cosh(beta * t) ** -1
    om = -mu * beta * np.tanh(beta * t)
    return a, om