def is_choked(p_c, p_e, gamma):
    """Determine whether the nozzle flow is choked.

    See :ref:`choked-flow-tutorial-label` for details.

    Reference: Rocket Propulsion Elements, 8th Edition, Equation 3-20.

    Arguments:
        p_c (scalar): Nozzle stagnation chamber pressure [units: pascal].
        p_e (scalar): Nozzle exit static pressure [units: pascal].
        gamma (scalar): Exhaust gas ratio of specific heats [units: dimensionless].

    Returns:
        bool: True if flow is choked, false otherwise.
    """
    return p_e / p_c < (2 / (gamma + 1)) ** (gamma / (gamma - 1))
