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Re: array handling [message #52122 is a reply to message #52121]

Sat, 06 January 2007 08:47

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Brian Larsen writes:

> Something I have always wondered is the difference between using
> finite() and just using ne?
>
> As an example:
> IDL> array = [ 1.0, 2.0, !Values.F_NAN, 4.0, !Values.F_NAN ]
> IDL> Print, Where( NOT Float( Finite(array) ) )
> 2 4
> IDL> print, where(array ne array)
> 2 4
>
> What is the fundamental difference here? Speed? Style? or something
> else entirely?

I don't know the answer, but I would guess the latter formulation
would lead some programmers to a general feeling of unease
regarding treating things that aren't numbers as if they were.
There are no hard and fast rules for such things, I don't think,
so you are at the mercy of programmers you don't know and
implementations that could, I guess, change in the future.

Plus, you get that damn "Arithmetic error: Floating illegal operation"
message when you try it. That generally causes a loss of confidence
among customers. :-(

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: array handling By: news.qwest.net on Mon, 08 January 2007 09:43
		Re: array handling By: David Fanning on Sat, 06 January 2007 08:51
		Re: array handling By: David Fanning on Sat, 06 January 2007 08:47
		Re: array handling By: Michael Galloy on Sat, 06 January 2007 08:39
		Re: array handling By: Brian Larsen on Sat, 06 January 2007 08:15
		Re: array handling By: David Fanning on Sat, 06 January 2007 07:01
		Re: array handling By: Brian Larsen on Thu, 11 January 2007 07:27

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