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Re: NA and NaN
From: |
Francesco Potorti` |
Subject: |
Re: NA and NaN |
Date: |
Wed, 12 Mar 2008 16:20:14 +0100 |
>> Thank you. I use both Octave 2.1 and Octave 3.0, and I had not tried
>> both. I would appreciate someone to answer my previous questions
>> nonetheless, as there is so much code around written for octave 2.1.
>In what version do you see that isnan(NA) gives 'false'? I have never
>observed this behaviour, so I was quite surprised by your questions.
Octave 2.1 does this. It is intended, as documented in the manual.
Octave 3 behaves differently. This should mean that I can use NA for
missing values and use the nan* functions from the statistics and nan
packages, which is good. Is this correct?
>> However, in light of Søren's observation, would it preferable to use NA
>> instad of NaN for missing values? What about octave-forge packages
>> "statistics" and "nan"? What about Matlab compatibility?
>Matlab doesn't have NA, so compatibility can be an issue, depending on
>the situation. The interpolation code (eg. 'interp2') uses NA when it
>performs extrapolation. In matlab NaN is used. Here there are no
>compatibility issues. Personally, I always use NA, when I'm missing
>data, and I never really understood how NaN is a good indicator of the
>same.
I would like to do the same in my code. What about saved data? If NA
is a NaN, Matlab should have no problems reading binary data. However,
it should give an error on ascii data. Is this the case?
>From a more general point of view, is it true that NA is only used by
Octave and R, while the rest of the world uses Nan?
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