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x*x versus x^2 [message #61206]

Wed, 09 July 2008 09:32

Conor
Messages: 138
Registered: February 2007

Senior Member

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?

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[Message index]

		x*x versus x^2 By: Conor on Wed, 09 July 2008 09:32
		Re: x*x versus x^2 By: Sven Geier on Sat, 12 July 2008 12:30

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