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Re: mean() function [message #46934 is a reply to message #46933]

Tue, 10 January 2006 15:09

Paul Van Delst[1]
Messages: 1157
Registered: April 2002

Senior Member

Fï¿½LDY Lajos wrote:
> Hi,
>
> have you tried mean(y,/double)?

Even regular old single worked for me:

IDL> y = fltarr(1008879)+35
IDL> id = where(y ne 35, cc)
IDL> print, cc
0
IDL> print, mean(y)
% Compiled module: MEAN.
% Compiled module: MOMENT.
35.0000
IDL> print, mean(y[0:400000])
35.0000

Maybe it's version related? I noticed that biocpu used () rather than [] for array
indexing. Maybe an earlier version of IDL had a MEAN() function that didn't use a
compensated summation algorithm? The OP mean from 0->400000 that worked suggests that's
not the case, but who knows? Anyway....

IDL> print, !version
{ x86 linux unix linux 6.0.3 Feb 26 2004 32 64}

paulv

>
> regards,
> lajos
>
>
> On Tue, 10 Jan 2006 biocpu@yahoo.com wrote:
>
>
>> The following looks very odd. Have any clues?
>>
>> IDL> y = fltarr(1008879)+35
>> IDL> id = where(y ne 35, cc)
>> IDL> print, cc
>> 0
>> ; so y is strictly 35.0 BUT
>> IDL> print, mean(y)
>> 35.5249
>>
>> IDL> print, mean(y(0:400000))
>> 35.0000
>>
>> Thanks,
>>
>>

--
Paul van Delst
CIMSS @ NOAA/NCEP/EMC

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[Message index]

		Re: mean() function By: Maarten[1] on Thu, 12 January 2006 03:07
		Re: mean() function By: Paolo Grigis on Wed, 11 January 2006 06:19
		Re: mean() function By: Nigel Wade on Wed, 11 January 2006 01:49
		Re: mean() function By: Kenneth P. Bowman on Tue, 10 January 2006 19:22
		Re: mean() function By: biocpu on Tue, 10 January 2006 16:18
		Re: mean() function By: Paul Van Delst[1] on Tue, 10 January 2006 15:13
		Re: mean() function By: Paul Van Delst[1] on Tue, 10 January 2006 15:09
		Re: mean() function By: David Fanning on Tue, 10 January 2006 15:07
		Re: mean() function By: K. Bowman on Tue, 10 January 2006 15:00
		Re: mean() function By: Foldy Lajos on Tue, 10 January 2006 14:53
		Re: mean() function By: R.Bauer on Sun, 15 January 2006 00:58
		Re: mean() function By: savoie on Thu, 12 January 2006 08:49

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