Beefy Boxes and Bandwidth Generously Provided by pair Networks
more useful options
 
PerlMonks  

Re^2: NaNs are true (NaN == 0 -> true? Really?)

by BrowserUk (Pope)
on Feb 27, 2011 at 07:48 UTC ( #890380=note: print w/ replies, xml ) Need Help??


in reply to Re: NaNs are true (!"NaN")
in thread NaNs are true

That's all very logical, except that at the end you seem to have arrived at the situation where you would have an implicit test of a NaN against zero be true?

NaN == 0 -> true cannot be right.


Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.


Comment on Re^2: NaNs are true (NaN == 0 -> true? Really?)
Re^3: NaNs are true (NaN == 0 -> true? Really?)
by pajout (Curate) on Feb 27, 2011 at 11:50 UTC
    What about idea that NaN never matches numerical comparison?
    NaN == 0 #false NaN != 0 #false NaN == NaN #false NaN != NaN #false

      I think all of those are correct, though not particularly useful. They should also prompt (at least) a warning, though I think a catchable exception is better.

      You also have to be careful to distinguish between a variable containing NaN, and a constant NaN I think.

      That is, I think the only time any comparison involving a variable containg NaN should result in a true value, is if it is compared against a predefined constant NaN; were one to be provided. Though an isNaN( $x ) function or equivalenly $x->isNan() method would serve the same purpose and be less likely to confuse.


      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://890380]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others rifling through the Monastery: (12)
As of 2014-07-10 11:12 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    When choosing user names for websites, I prefer to use:








    Results (207 votes), past polls