| Re: histogram produces extra bin in 64-bit IDL 8.0 [message #76023] |
Fri, 13 May 2011 07:50  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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EddE writes:
> Curiouser and curiouser - 32 and 64 bit modes on the same machine act
> identically, but another machine behaves differently....
I do notice in this code that there is a discrepancy in the
type of data and the type of the binsize. Histogram is
notorious for having difficulty when the data types
don't match. Hence, the Convert_To_Type function
in the Coyote Library.
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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| Re: histogram produces extra bin in 64-bit IDL 8.0 [message #76026 is a reply to message #76025] |
Fri, 13 May 2011 07:13  |
penteado
Messages: 866
Registered: February 2018
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Senior Member
Administrator |
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On May 13, 11:08 am, David Fanning <n...@idlcoyote.com> wrote:
> Eric Tittley writes:
>> Consider the following code:
>> IDL> D=randomu(32,3200);
>> IDL> N=histogram(D,min=0.,max=1.,binsize=0.1,Locations=X)
>
>> In IDL 32-bit:
>> IDL> print, size(N)
>> 1 10 3 10
>> IDL> print, X
>> 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
>> IDL> print, !version
>> { x86 linux unix linux 8.0 Jun 18 2010 32 64}
>
>> In 64-bit IDL:
>> IDL> print, size(N)
>> 1 11 3 11
>> IDL> print, X
>> 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
>> IDL> print, !version
>> { x86_64 linux unix linux 8.0 Jun 18 2010 64 64}
>
>> As you can see, the 64-bit version produces an extra erroneous bin, contrary to the what is expected from the help pages for histogram.
>
> Undoubtedly a consequence of the razor's edge:
>
> http://www.idlcoyote.com/math_tips/razoredge.html
That is what I was thinking, considering both results to be normal and
expected. But I was wondering what changed between versions.
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| Re: histogram produces extra bin in 64-bit IDL 8.0 [message #76027 is a reply to message #76026] |
Fri, 13 May 2011 07:08 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Eric Tittley writes:
> Consider the following code:
> IDL> D=randomu(32,3200);
> IDL> N=histogram(D,min=0.,max=1.,binsize=0.1,Locations=X)
>
> In IDL 32-bit:
> IDL> print, size(N)
> 1 10 3 10
> IDL> print, X
> 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
> IDL> print, !version
> { x86 linux unix linux 8.0 Jun 18 2010 32 64}
>
> In 64-bit IDL:
> IDL> print, size(N)
> 1 11 3 11
> IDL> print, X
> 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
> IDL> print, !version
> { x86_64 linux unix linux 8.0 Jun 18 2010 64 64}
>
> As you can see, the 64-bit version produces an extra erroneous bin, contrary to the what is expected from the help pages for histogram.
Undoubtedly a consequence of the razor's edge:
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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| Re: histogram produces extra bin in 64-bit IDL 8.0 [message #76105 is a reply to message #76023] |
Wed, 18 May 2011 08:04 |
war
Messages: 21
Registered: December 2003
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Junior Member |
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I just posted the following message but then I saw there just was a
topic about more or less the similar problem. In my case, it is just
about using different binsize and max.
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.
Thanks,
Andry
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