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Element-wise multiplication of duration and double array

Asked by Amir Rashidi on 11 Oct 2015
Latest activity Answered by Rob Purser on 12 Oct 2015

Hi, I try to calculate the energy in a time series dataset. I calculate the power for each record i.e. every hour. Now i would like to compute the energy for each row. I used the :diff" to find the duration for each row and then multiply that duration to power value to calculate the energy. however the final product is duration format. could you please help me with that?

Date	Power (W)
'01-Jan-2005 00:00:00'	362374.8161
'01-Jan-2005 01:00:00'	290296.1116
'01-Jan-2005 02:00:00'	96520.39268
'01-Jan-2005 03:00:00'	96491.92618
'01-Jan-2005 04:00:00'	96420.53794

the code I used so far:

A = diff(dispt);
P(1, : ) = [];
E = P.*A;

  10 Comments

It appears the doc 'See Also' section is quite lacking in the duration object section -- couldn't find any of those w/o knowing they existed already.

But, does look like that's the manner by which to get there.

I hadn't really developed any being any particular representation; I've not got enough machine to be able to load/run the latter revisions so all I can do is try to guess as best as can from the doc's what/how to get from here to there...as noted, there being no links from either datetime nor duration to the hours|minutes|seconds, etc., conversion routines was just hoping the casting operations would manage...

The cross reference is definitely lacking.

Indeed...obtw, on the comment regarding datenum resolution; they can get to about 10 usec...

>> eps(now)*86400/1e-6
ans =
 10.0583
>>

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1 Answer

Answer by Rob Purser on 12 Oct 2015

The result of the diff on dispt (which I assume is a datetime) is a duration. You will want to convert the duration to a double before doing math on it using a function like hours or seconds.

-Rob

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