def running_std(self):
        '''
            returning the running standard deviation for Tensorplex Logging
            Returns:
                numpy array of running standard deviation
        '''
        running_std = ((self.running_sumsq / self.count) 
                     - (self.running_sum / self.count).pow(2)).pow(0.5)
        return running_std.cpu().numpy()

            returning the running standard deviation for Tensorplex Logging
            Returns:
                numpy array of running standard deviation
        
surreal/model/z_filter.py