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Re: Unexpected rebin behavior [message #36368 is a reply to message #36271]

Wed, 03 September 2003 09:31

James Kuyper
Messages: 425
Registered: March 2000

Senior Member

Mike Chinander wrote:
>
> Performing rebin on 2-d (or any higher dimension) integer arrays sometimes
> give results I didn't expect. Here's a trivial example array:
>
> IDL> help, b
> B INT = Array[2, 2]
>
> IDL> print, b
> 8 9
> 10 13
>
> Minifying this to a 1x1 array with rebin gives:
>
> IDL> print, rebin(b,1,1)
> 9
>
> But,
>
> IDL> print, fix(total(b)/4)
> 10

What it's doing is total(b/4), rather than total(b)/4. This has the
advantage of handling large numbers without producing overflow. It has
the disadvantage of underflowing for very small numbers, and producing
wierd results when re-binning integer data.

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[Message index]

		Unexpected rebin behavior By: mchinand on Wed, 03 September 2003 09:20
		Re: Unexpected rebin behavior By: mchinand on Wed, 03 September 2003 10:02
		Re: Unexpected rebin behavior By: James Kuyper on Wed, 03 September 2003 09:31

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