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bonus

Joined: 07 Sep 2011
Posts: 2

Posted: Wed Sep 07, 2011 10:24 am    Post subject: Differentiate curve based on past time interval

Is there a way to differentiate a curve based on the past = previous time interval?
 Code: y_j' = (y_j - y_j-1)/(x_j - x_j-1)

I'm working with non equally spaced rainfall time series, here in the form of the total rainfall depth:
 Code: 26-05-2011 17:28:19 0.1 26-05-2011 17:35:42 0.2 26-05-2011 20:27:53 0.3 26-05-2011 22:36:41 0.4 26-05-2011 22:39:16 0.5 26-05-2011 22:44:05 0.6 26-05-2011 22:51:35 0.7 26-05-2011 22:53:43 0.8 26-05-2011 22:56:56 0.9 26-05-2011 23:00:07 1.0 26-05-2011 23:02:31 1.1 26-05-2011 23:03:39 1.2 etc.

The rainfall intensity equals the slope of the rainfall depth in the past interval, whereas the "Differentiate a Curve" command is based on the central difference
 Code: y_j' = (y_j+1 - y_j-1)/(x_j+1 - x_j-1)

which doesn't really fit.

Thank you!

Joined: 24 Jun 2003
Posts: 2023
Location: Vicksburg, Mississippi

 Posted: Wed Sep 07, 2011 12:13 pm    Post subject: There's no way to do that but it would of course be an easy addition. Thanks for the suggestion._________________David Hyde support@dplot.com
bonus

Joined: 07 Sep 2011
Posts: 2

 Posted: Thu Sep 29, 2011 9:44 am    Post subject: If this is indeed an easy addition, it would be great to get it in one of the next releases. Thank you!

Joined: 24 Jun 2003
Posts: 2023
Location: Vicksburg, Mississippi

 Posted: Thu Sep 29, 2011 10:38 am    Post subject: It will be._________________David Hyde support@dplot.com
raswaim

Joined: 06 Jan 2005
Posts: 69
Location: Houston, TX

 Posted: Sat Mar 17, 2012 7:10 pm    Post subject: Is this feature restricted to only curves that have regular intervals? With the latest release I seem to only get the pop-up to choose the method if the data is regular. I differentiated a sample generated curve and got the popup, but after I remove a couple points from the curve I no longer get any options when I select the same curve to differentiate again._________________- RAS

Joined: 24 Jun 2003
Posts: 2023
Location: Vicksburg, Mississippi

 Posted: Sat Mar 17, 2012 7:14 pm    Post subject: Yes, but that is an error of omission on my part rather than a logical restriction. I'll fix this in the next release._________________David Hyde support@dplot.com
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