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Re: Array indexing "Feature" [message #28448 is a reply to message #28447]

Thu, 13 December 2001 07:23

Liam E. Gumley
Messages: 378
Registered: January 2000

Senior Member

Andrew Cool wrote:
> One of my colleagues has noted something apparently screwy in the
> indexing of
> arrays.
>
> e.g. a = indgen(10)
> print, a(9) -> you get 9
> print, a(10) -> you get an error, as expected for a zero-based
> index
>
> but if you access the array with the index as a vector, it seems to
> truncate the index to the maximum allowable:
>
> print, a([10]) -> you get 9
> print, a([666]) -> you get 9
>
> Similarly:
>
> print, a(-1) -> you get an error
> print, a([-1]) -> you get 0
>
> This feature holds good for IDL 5.2 and 5.4 on OpenVMS and for 5.5 on
> Windows.
>
> Where, Oh where in the manuals does it describe this?

For what it's worth, this behavior is documented in "Practical IDL
Programming" on page 30 (section 2.4 "Array Indexing").

Cheers,
Liam
Practical IDL Programming
http://www.gumley.com/

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[Message index]

		Re: Array indexing "Feature" By: Pavel A. Romashkin on Mon, 17 December 2001 09:40
		Re: Array indexing "Feature" By: k-bowman on Thu, 13 December 2001 08:35
		Re: Array indexing "Feature" By: Liam E. Gumley on Thu, 13 December 2001 07:23
		Re: Array indexing "Feature" By: Paul van Delst on Thu, 13 December 2001 06:17
		Re: Array indexing "Feature" By: David Fanning on Wed, 12 December 2001 16:48
		Re: Array indexing "Feature" By: Kristine Hensel on Wed, 12 December 2001 16:31
		Re: Array indexing "Feature" By: Andrew Cool on Wed, 12 December 2001 16:10
		Re: Array indexing "Feature" By: Jeff Jones on Wed, 12 December 2001 15:03
		Re: Array indexing "Feature" By: Paul van Delst on Wed, 12 December 2001 14:44
		Re: Array indexing "Feature" By: Craig Markwardt on Wed, 12 December 2001 14:28
		Re: Array indexing "Feature" By: David Fanning on Wed, 12 December 2001 14:12

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