Real-Time Expressions: math.timeDerivative


math.timeDerivative calculates the change in value between adjacent data points divided by the change in time between adjacent data points in a data stream


=math.timeDerivative([data stream], "unit")
where "unit" can be "ns", "us", "ms", "sec", "min", "hr", "day"


data_stream values = (1, 23, 43) with
timestamps (2017-06-13T15:48:05Z, 2017-06-13T15:48:16Z, 2017-06-13T15:48:21Z)
(timestamp 1 and 2 are 11 seconds apart, timestamps 2 and 3 are 5 seconds apart)
=math.timeDelta([data_stream], "sec")
creates a new data stream = ( (23-1)/11, (43-23)/5 ) =  (2, 4)

Feedback and Knowledge Base