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Re: handling NaN


From: Thomas S. Shores
Subject: Re: handling NaN
Date: Tue, 30 Jul 2002 18:16:51 -0500

Heber Farnsworth wrote:

> I'm have trouble with NaN values.  I don't mind that they come up
> occasionally but I need to know how to get rid of them.  I'm evaluating
> a function at various points and I need to pick the maximum point.
> Occasionally the point will be an illegal one and it's difficult to
> predict when that will happen.  Obviously I don't want that point.
> However the following behavior of octave makes it difficult to get the
> point I do want.
>
> $ octave -q
> octave:1> f = [1 2 3 NaN]
> f =
>
>     1    2    3  NaN
>
> octave:2> max(f)
> ans = NaN
> octave:3> min(f)
> ans = NaN
> octave:4>
>
> If NaN is both the min and max of any vector it is contained in then how
> do I get octave to return the value I want (3 in this case)?
>
> Heber
>
> -------------------------------------------------------------
> Octave is freely available under the terms of the GNU GPL.
>
> Octave's home on the web:  http://www.octave.org
> How to fund new projects:  http://www.octave.org/funding.html
> Subscription information:  http://www.octave.org/archive.html
> -------------------------------------------------------------

Try removing the NaNs first, e.g.,

f = [1 2 3 NaN]
max(f(!isnan(f)))
min(f(!isnan(f)))

Hope this helps

Tom Shores





-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
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