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Re: coherence test implementation [message #15420 is a reply to message #15336]

Thu, 13 May 1999 00:00

Dick Jackson
Messages: 347
Registered: August 1998

Senior Member

(quick, before they wake up in Australia! :-)

Hi again,

Dick Jackson wrote:
>
> You piqued my curiosity, since you're right, there had to be a more
> efficient way! My attached coherence.pro should do the trick, and I
> clock it at about 60 times faster with a 300x300 test.
> [...]
> Generalizing coherence.pro to allow variable 'width' [...]
> wouldn't be hard

I looked at my code again, and realized I was duplicating the function of
the IDL CONVOL routine. That sure simplified things! (and in my 300x300
test, cut time in half yet again) Adding the 'width' idea was trivial. I
think writing helpful comments was the worst part. :-)

And, as with any Good Thing in IDL, it can be written in one line:

coh = Sqrt((Convol(array ^ 2.0, Replicate(1, width, width)) $
- (Convol(Float(array), Replicate(1, width, width))^2 $
/ (width ^ 2))) $
/ ((width ^ 2)-1))

(the attached .pro is much easier to read and understand)

Enjoy.

Cheers,
--
-Dick

Dick Jackson Fanning Software Consulting, Canadian Office
djackson@dfanning.com Calgary, Alberta Voice/Fax: (403) 242-7398
Coyote's Guide to IDL Programming: http://www.dfanning.com/

Attachment: coherence.pro
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[Message index]

		coherence test implementation By: Mark Rehbein on Thu, 13 May 1999 00:00
		Re: coherence test implementation By: Struan Gray on Thu, 13 May 1999 00:00
		Re: coherence test implementation By: eddie haskell on Thu, 13 May 1999 00:00
		Re: coherence test implementation By: Dick Jackson on Thu, 13 May 1999 00:00
		Re: coherence test implementation By: Craig Markwardt on Thu, 13 May 1999 00:00
		Re: coherence test implementation By: Dick Jackson on Thu, 13 May 1999 00:00

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