RE: Q on NaN

[Drew Adams]

I said this:

    (condition-case nil (setq foo (/ 0.0 0.0)) (arith-error nil))
    In older versions of Emacs (at least prior to April 2005 CVS), 
    this would evaluate to nil. Now, it evaluates to -0.0NaN.
    I can modify the code like so:
    (and (condition-case nil (setq foo (/ 0.0 0.0)) (arith-error nil))
         (bar foo)) ; foo must be a number, not a NaN
    What function do I use for bar? 
    `numberp' doesn't work, since (numberp -0.0NaN) is non-nil. 

To make the point simpler:

(numberp (/0.0 0.0)) returns t. That seems like a bug to me.