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[IDV #ELV-470278]: SIMPLE TIME DIFFERENCE

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  • Subject: [IDV #ELV-470278]: SIMPLE TIME DIFFERENCE
  • Date: Fri, 03 Apr 2009 05:53:43 -0600
Hi Riccardo,
Sorry for the delay in getting back to you. This just slipped through the 
cracks of our support box.

> Description of problem: I STARTED USING IDL TODAY. WHAT I'D LIKE TO DO IS 
> VERY SIMPLE: I HAVE A GRIB FILE WITH CUMULATED PRECIPITATIONS FROM ECMWF 
> OPERATIONAL MODEL, AND I WANT TO MAKE A "SIMPLE TIME DIFFERENCE" IN ORDER TO 
> SEE THE CUMULATED VALUE IN 12 HOURS: T24-T12, T36-T24 AND SO ON. IT APPEARS A 
> SMALL WINDOWS REQUESTING "TIME1" AND "TIME2", BUT I DON'T UNDERSTAND WHICH 
> VALUES I HAVE TO PUT INSIDE. THANK YOU VERY MUCH IN ADVANCE. RICCARDO
> 

The latest version of the IDV has a formula Formulas->Grids->Time Steps->Time 
step difference
that takes a grid field and does a difference so that:
Data(T) = Data(T)-Data(T-1)

Note - the -1 offset is the index of the time, e.g., -3 is not -3 hours but is 
the time 3 time stpes prior. This is not the absolute time. 

One can also specify an arbitrary (index) offset using another formula.
Attached is a plugin (install it through the Tools->Plugin Manager  dialog
under its File menu).

This has a formula that prompts the user or an offset. It also has a fix to a 
problem
in our released jython library (it call a routine fixedtimeStepDifference not 
the
normal (and broken) timeStepDifference).

-Jeff



Ticket Details
===================
Ticket ID: ELV-470278
Department: Support IDV
Priority: Critical
Status: Closed

Attachment: timestepdifference.jar
Description: Binary data