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Re: efficient kernel or masking algorithm ? UPDATE [message #23921 is a reply to message #23919]

Sun, 25 February 2001 12:39

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

"Martin Downing" <martin.downing@ntlworld.com> writes:

>
> I was wandering through new Craig's IDL archive site (which is brilliant by
> the way) and came across this question asking for an efficient way of
> calculating the loacal standard deviation in an array. It seemed to me that
> the thread had not reached a full solution so perhaps some of you might be
> interested in this method which is very fast. It is based on the crafty
> formula for variance:
> variance = (sum of the squares)/n + (square of the sums)/n*n
>
> [ apologies if this is going over old ground !]

Hi Martin--

This looks like a great way to do things. Now if we could only
translate those bloomin' British English spellings! NEIGHBOURHOOD
indeed. :-)

As a side note, I believe that your message would have actually shown
up as a reply to Richard's or JD's messages in the archive, if you had
placed the Message-ID of their article in the References header of
yours. I've tried it here. We'll see if it works.

Craig

--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
------------------------------------------------------------ --------------

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[Message index]

		Re: efficient kernel or masking algorithm ? UPDATE By: Craig Markwardt on Mon, 26 February 2001 10:51
		Re: efficient kernel or masking algorithm ? UPDATE By: Martin Downing on Mon, 26 February 2001 07:32
		Re: efficient kernel or masking algorithm ? UPDATE By: Martin Downing on Mon, 26 February 2001 02:21
		Re: efficient kernel or masking algorithm ? UPDATE By: Martin Downing on Mon, 26 February 2001 02:21
		Re: efficient kernel or masking algorithm ? UPDATE By: Martin Downing on Mon, 26 February 2001 02:00
		Re: efficient kernel or masking algorithm ? UPDATE By: Martin Downing on Mon, 26 February 2001 01:52
		Re: efficient kernel or masking algorithm ? UPDATE By: John-David T. Smith on Sun, 25 February 2001 19:00
		Re: efficient kernel or masking algorithm ? UPDATE By: Craig Markwardt on Sun, 25 February 2001 12:39
		Re: efficient kernel or masking algorithm ? UPDATE By: Martin Downing on Sun, 25 February 2001 10:44
		Re: efficient kernel or masking algorithm ? UPDATE By: PMan on Tue, 23 July 2013 13:35

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