public Speed speed_sound()
    {
        if (Environment.Is64BitProcess)
        {
            if (!(0 <= Q() && Q() <= 1))
            {
                return(Speed.FromMetersPerSecond(CoolPropPINVOKE64.AbstractState_speed_sound(swigCPtr)));
            }
        }
        else
        {
            if (!(0 <= Q() && Q() <= 1))
            {
                return(Speed.FromMetersPerSecond(CoolPropPINVOKE.AbstractState_speed_sound(swigCPtr)));
            }
        }

        return(Speed.Zero);
    }