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Re: IDL and Macs. Speed is not only about squared roots [message #49303 is a reply to message #49301]

Fri, 14 July 2006 04:37

Maarten[1]
Messages: 176
Registered: November 2005

Senior Member

jgc wrote:
[. . .]
> However there is more in life than squared roots, so I was dissapointed
> to see that a complex program, involving large array manipulation,
> input and output, and loops reduced to a minimum, took almost double
> the time in the Mac than in the windows PC. This is a energy balance
> model for snow ablation over a glacier in the Alps
> (http://www.arolla.ethz.ch/snowdem.html).
>
> One summer simulation took 22 minutes on IDL 6.0 in the windows PC 1.4
> GHz and 42 minutes on the Mac Intel 2.16 GHz with IDL 6.2. Almost
> double in a much more powerful computer! IDL 6.3 seems slightly
> better but still slower (I'm waiting for the full license to test it).

6.2 is PPC, and therefore runs under emulation. You'll need 6.3/Mac OS
X/Intel to be able to judge this at all. Rosetta rears its head again.

> I did additional texts such as repeatig more complex processes (my
> shading algorithm, http://www.ittvis.com/codebank/search.asp?FID=141).
> Here the mac outperforms the pc. Thus, obviously there must be just a
> few inefficient processess for the Mac, which slow down the wole thing.

Given the fact that you didn't use the real native thing, I think
you're jumping to conclusions. If you're sure that you use the real
(native) thing, then post some more results. If you're curious where
the time is spent in your program, I suggest you use the profiler
(search this newsgroup, of just use the IDL manual). Highly insightful,
and allows you to focus on the slow parts when optimizing.

Maarten

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[Message index]

		Re: IDL and Macs. Speed is not only about squared roots By: Karl Schultz on Fri, 14 July 2006 08:20
		Re: IDL and Macs. Speed is not only about squared roots By: Maarten[1] on Fri, 14 July 2006 07:18
		Re: IDL and Macs. Speed is not only about squared roots By: jgc on Fri, 14 July 2006 06:26
		Re: IDL and Macs. Speed is not only about squared roots By: jgc on Fri, 14 July 2006 06:02
		Re: IDL and Macs. Speed is not only about squared roots By: Maarten[1] on Fri, 14 July 2006 04:37

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