def mahalanobis(self):
        """"
        Mahalanobis distance of measurement. E.g. 3 means measurement
        was 3 standard deviations away from the predicted value.
        Returns
        -------
        mahalanobis : float
        """
        if self._mahalanobis is None:
            self._mahalanobis = sqrt(float(dot(dot(self.y.T, self.SI), self.y)))
        return self._mahalanobis
"
        Mahalanobis distance of measurement. E.g. 3 means measurement
        was 3 standard deviations away from the predicted value.
        Returns
        -------
        mahalanobis : float
        
trackers/ocsort_tracker/kalmanfilter.py