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Re: Array has too many elements? [message #37493 is a reply to message #37489]

Mon, 22 December 2003 10:32

Jamie
Messages: 4
Registered: December 2003

Junior Member

On Fri, 19 Dec 2003, Jonathan Greenberg wrote:

> So, any suggestions for the best way of getting around these limitations (I
> mean, without having to buy a 64-bit machine) -- how about chopping the
> array up into smaller blocks and performing for-next loops -- processing
> part of the array, writing the results, and then processing the next part?
> Are there better ways than this?

Nope. Frankly, once you start working with arrays that consume 1GB of
memory, you are in for a whole world of trouble. IDL is a flexible,
non-compiled language which means that commands are expanded into a
working stack where copies are often made. Working with big arrays also
means becoming proficeint in using the NOZERO keyword, the
REPLICATE_INPLACE procedure, the NO_COPY keyword, and the TEMPORARY
function. You haven't really told us what exactly you are trying to do...
I hope that you don't have too many zeros in your arrays ;)

As far as I know, the array size limit in IDL on *all* platforms is still
2^31-1 (2 GB). Overcoming this is more-or-less impossible even with a 64
-bit machine. In short, you need to break up large arrays and be careful
with your indexing. The best case would be if you can effectively reduce
the volume of the data as you loop.

Keep in mind that IDL stands for "interactive data language." While, it
is a capable programming environment for visualizing data, working with
arrays that consume 1-2 GB is not quite mainstream yet. In another 2
years, this probably won't be such an issue...

Jamie

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[Message index]

		Re: Array has too many elements? By: JD Smith on Mon, 22 December 2003 14:01
		Re: Array has too many elements? By: Jonathan Greenberg on Mon, 22 December 2003 13:35
		Re: Array has too many elements? By: Jamie on Mon, 22 December 2003 10:32
		Re: Array has too many elements? By: Jonathan Greenberg on Fri, 19 December 2003 11:54
		Re: Array has too many elements? By: Michael Wallace on Fri, 19 December 2003 08:46
		Re: Array has too many elements? By: Michael Wallace on Fri, 19 December 2003 08:32
		Re: Array has too many elements? By: Jamie on Fri, 19 December 2003 01:23
		Re: Array has too many elements? By: Bringfried Stecklum on Fri, 19 December 2003 03:00
		Re: Array has too many elements? By: Jonathan Greenberg on Fri, 19 December 2003 00:51

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