Re: isnumeric (NaN) = true !?

[David Grundberg]

Søren Hauberg wrote:
> tor, 25 03 2010 kl. 14:40 +0100, skrev Matthias Brennwald:
>   
> > What is the logic behind this:
> >
> >         isnumeric (NaN) = 1
> >
> > I believe that "NaN" means "not a number". How can something which is
> > "not a number" be numeric? What is the logic behind this?
> >     
>
> I wouldn't exactly call it logic, but one reason for this behaviour is
> that Matlab does the same.
>
> In general, when it comes to NaN's you have to deal with them using
> 'isnan'.
>
> Søren

You're all confusing the terminology here. Stop trying to apply common 
sense and intuition, nothing good has ever come out of it. (joke) The 
isnumeric function checks the *class* of a variable and has nothing to 
do with the *value* of the variable. One class that isnumeric considers 
true is "double". "Not a number" is a value, not a class. Since the 
value "not a number" is of class "double", the variable is numeric.

hth,
David