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Re: Optimization Question: Sum at each element of array [message #75083]

Tue, 15 February 2011 12:15

James[2]
Messages: 44
Registered: November 2009

Member

On Feb 14, 9:58 pm, Charles Steinhardt <charles.steinha...@ipmu.jp>
wrote:
> Hello,
>
> I'm trying to optimize the following:
>
> for i=0, 100 do begin
> y = y + myfunc(x, x + sigma * (i-50)/10.0, P[2]*myfunc2(x + sigma
> * (i-50)/10.0), sigma)
> endfor
>
> Here, x, y, and sigma are arrays of the same cardinality. I know the
> for loop is slow in IDL compared to array operations, but I'm having
> problems finding a faster way to do this. Is it really faster to make
> an array of findgen(101) and then do some sort of summation over
> that?
>
> I'm hoping somebody has run into this before - I'd appreciate any
> advice you have!
>
> Thank you,
>
> -Charles

One simple optimization step is to replace:

y = y + (blahblahblah...)

with

y += (blahblahblah...)

This avoids making IDL acquire memory each iteration to store the
result of y + (blahblahblah...).

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[Message index]

		Re: Optimization Question: Sum at each element of array By: James[2] on Tue, 15 February 2011 12:15
		Re: Optimization Question: Sum at each element of array By: Jeremy Bailin on Tue, 15 February 2011 06:31
		Re: Optimization Question: Sum at each element of array By: Brian Daniel on Tue, 15 February 2011 05:09

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