def update(self, elapsed = 0.0):
        if self._lastV and elapsed:
            newDeltaV = (self._v - self._lastV) / elapsed
            if self._deltaV:
                self._deltaV = gamma_filter(self._deltaV, newDeltaV, self._g)
            else:
                self._deltaV = newDeltaV
        self._lastV = self._v
update the statistic delta's according to the elapsed period of time
dataset/ETHPy150Open concurrence/concurrence/lib/concurrence/statistic.py/Statistic.update