@property
    def R1_2(self):
        return self._R1_2
Returns:
dataset/ETHPy150Open rlabbe/filterpy/filterpy/kalman/square_root.py/SquareRootKalmanFilter.R1_2--crossover with--dataset/ETHPy150Open meraki-analytics/cassiopeia/cassiopeia/type/core/match.py/ParticipantTimelineData.ten_to_twenty