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Re: Pass by value and performance [message #46784 is a reply to message #46719]

Fri, 16 December 2005 09:29

Rick Towler
Messages: 821
Registered: August 1998

Senior Member

Kenneth P. Bowman wrote:
> A cautionary note on argument passing ...
>
> I have a large code that does a lot of interpolation in
> multi-dimensional arrays. Being a clever IDL programmer (too clever by
> half, as it turns out), I package these arrays into structures along
> with various information about the arrays. When these arrays are then
> passed, for example, into INTERPOLATE, as
>
> result = INTERPOLATE(data.array, x, y, z)
>
> the array is passed by value, which entails making a copy of the array.
> When these arrays get large, this causes a big performance hit. So, I
> am in the process of making my code less clever (and uglier) but much
> faster.

It's nice that we have to worry about these things in IDL.

I'm working in MATLAB right now helping a colleague run a large
simulation and managing memory when you can only pass by value is a real
pain/annoyance. Talk about a performance hit:

??? Error using ==> zeros
Out of memory. Type HELP MEMORY for your options.

The inability to pass by reference in MATLAB is *insane*. An annoyance
when writing everyday code, a real hindrance when array sizes balloon.

-Rick

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[Message index]

		Pass by value and performance By: Kenneth P. Bowman on Tue, 13 December 2005 21:00
		Re: Pass by value and performance By: Dick Jackson on Mon, 19 December 2005 09:33
		Re: Pass by value and performance By: Rick Towler on Fri, 23 December 2005 10:04
		Re: Pass by value and performance By: David Fanning on Fri, 16 December 2005 11:23
		Re: Pass by value and performance By: Rick Towler on Fri, 16 December 2005 11:03
		Re: Pass by value and performance By: JD Smith on Fri, 16 December 2005 10:40
		Re: Pass by value and performance By: David Fanning on Fri, 16 December 2005 10:24
		Re: Pass by value and performance By: Rick Towler on Fri, 16 December 2005 09:29
		Re: Pass by value and performance By: Paolo Grigis on Fri, 16 December 2005 03:08
		Re: Pass by value and performance By: Antonio Santiago on Fri, 16 December 2005 02:24
		Re: Pass by value and performance By: JD Smith on Thu, 15 December 2005 13:04

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