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Re: counting bits [message #34106 is a reply to message #34105]

Mon, 17 February 2003 12:38

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Joe Foose (jfoose@ameritech.net) writes:

> In IDL, does anybody have any ideas of how to efficiently count all the bits
> that are set in an array of unsigned long integers? I'm not concerened with
> which bits are set, but just how many. thanks, joe.

Just of the top of my head, wouldn't something like this work:

IDL> total = 0.0
IDL> for j=0,31 do total = TOTAL((array AND 2^j) NE 0)
IDL> print, Fix(total)

Cheers,

David
--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@dfanning.com
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[Message index]

		Re: counting bits By: Craig Markwardt on Wed, 19 February 2003 21:31
		Re: counting bits By: Dick Jackson on Wed, 19 February 2003 07:47
		Re: counting bits By: Craig Markwardt on Tue, 18 February 2003 15:10
		Re: counting bits By: JD Smith on Tue, 18 February 2003 14:58
		Re: counting bits By: David Fanning on Tue, 18 February 2003 13:55
		Re: counting bits By: Rick Towler on Tue, 18 February 2003 13:27
		Re: counting bits By: JD Smith on Tue, 18 February 2003 11:56
		Re: counting bits By: eddie haskell on Tue, 18 February 2003 08:10
		Re: counting bits By: David Fanning on Mon, 17 February 2003 21:09
		Re: counting bits By: Craig Markwardt on Mon, 17 February 2003 20:45
		Re: counting bits By: JD Smith on Mon, 17 February 2003 15:54
		Re: counting bits By: David Fanning on Mon, 17 February 2003 12:41
		Re: counting bits By: David Fanning on Mon, 17 February 2003 12:38
		Re: counting bits By: JD Smith on Thu, 20 February 2003 07:43
		Re: counting bits By: JD Smith on Thu, 20 February 2003 07:24

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