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Re: x*x versus x^2 [message #61203 is a reply to message #61201]

Wed, 09 July 2008 09:43

Conor
Messages: 138
Registered: February 2007

Senior Member

On Jul 9, 12:32 pm, Conor <cmanc...@gmail.com> wrote:
> So I've been looking at execution time for various algorithms, and I
> found this interesting result:
>
> bigarr = fltarr(1000,1000)
>
> t1 = systime(/seconds)
> t = bigarr^2.0
> t2 = systime(/seconds)
> t = bigarr*bigarr
> t3 = systime(/seconds)
>
> print,t2-t1
> print,t3-t2
>
> IDL prints:
>
> 0.024163008
> 0.010262012
>
> Apparently multiplying an array by itself is twice as fast as using
> the carat operator! Anyone know why this is? Is it a memory issue or
> something?

This also holds true for array's smaller than the multi-threading
minimum size, so it isn't because multi-threading is being used in one
case but not the other...

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[Message index]

		Re: x*x versus x^2 By: Conor on Wed, 09 July 2008 10:10
		Re: x*x versus x^2 By: Bruce Bowler on Wed, 09 July 2008 09:57
		Re: x*x versus x^2 By: pgrigis on Wed, 09 July 2008 09:55
		Re: x*x versus x^2 By: Conor on Wed, 09 July 2008 09:43
		Re: x*x versus x^2 By: dzhang49 on Sat, 12 July 2008 09:25

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