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Re: HISTOGRAM, binsize, and max [message #76108 is a reply to message #76104]

Wed, 18 May 2011 07:23

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

andry writes:

> Can somebody explain why the following gives different number of
> elements with the HISTOGRAM function?
>
> IDL> hist_spd= HISTOGRAM(velocity[indb],binsize= .20,min=0.,max=1.40)
> IDL> print,hist_spd
> 6 16 23 0 0
> 0 0
> IDL> hist_spd= HISTOGRAM(velocity[indb],binsize= 20.,min=0.,max=140.)
> IDL> print,hist_spd
> 45 0 0 0 0
> 0 0 0
>
> (whatever velocity content is)
> My main concern is the number of elements returned by the function.
> The only difference between the 2 command is that I multiplied the
> binsize and max with 100. BUT they return 7 and 8 elements?
>
> I would expect they both return the same number of elements.

People expect a lot of things from computers, but the
computers don't always oblige. I think this is just the normal
weirdness with how computers represent numbers. It
turns out this is different from how humans apparently
do it. :-)

http://www.idlcoyote.com/math_tips/sky_is_falling.html
http://www.idlcoyote.com/math_tips/razoredge.html

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: HISTOGRAM, binsize, and max By: pgrigis on Wed, 18 May 2011 11:41
		Re: HISTOGRAM, binsize, and max By: pgrigis on Wed, 18 May 2011 11:33
		Re: HISTOGRAM, binsize, and max By: war on Wed, 18 May 2011 10:08
		Re: HISTOGRAM, binsize, and max By: pgrigis on Wed, 18 May 2011 08:22
		Re: HISTOGRAM, binsize, and max By: David Fanning on Wed, 18 May 2011 07:23
		Re: HISTOGRAM, binsize, and max By: penteado on Wed, 18 May 2011 07:16

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