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Re: MEDIAN and double? [message #30772]

Fri, 17 May 2002 19:49

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

"Pavel A. Romashkin" <pavel_romashkin@hotmail.com> writes:

> I always thought that MEDIAN in Double is just
>
> print, (the_data[sort(the_data)])[n_elements(the_data)/2]

That works for a single number, but the nice part about MEDIAN is that
it can be applied with a sliding window, as in,

ysmooth = median(y, window)

But, if your data have double precision then YSMOOTH is not always
high enough precision to respect the original data. Or, at least,
mine didn't.

For example, consider:

IDL> print, median(1d + 2.4d-9 + [0,0]) - 1
0.00000

Whoops!

Craig

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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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		Re: MEDIAN and double? By: Craig Markwardt on Fri, 17 May 2002 19:49
		Re: MEDIAN and double? By: thompson on Fri, 17 May 2002 15:18
		Re: MEDIAN and double? By: Pavel A. Romashkin on Fri, 17 May 2002 14:38

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