[Python-Dev] Why is nan != nan? (original) (raw)

Robert Kern robert.kern at gmail.com
Sun Mar 28 01:27:57 CET 2010

On 2010-03-27 13:36 , Adam Olsen wrote:

On Fri, Mar 26, 2010 at 17:16, Raymond Hettinger <raymond.hettinger at gmail.com> wrote:

Of the ideas I've seen in this thread, only two look reasonable: * Do nothing. This is attractive because it doesn't break anything. * Have float.eq(x, y) return True whenever x and y are the same NaN object. This is attractive because it is a minimal change that provides a little protection for simple containers. I support either of those options. What's the flaw in using isnan()?

There are implicit comparisons being done inside list.contains() and other such methods. They do not, and should not, know about isnan().

-- Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco

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