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

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?)

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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` [download]	[reply] [d/l]
Re^4: NaNs are true (NaN == 0 -> true? Really?) by BrowserUk (Patriarch) on Feb 27, 2011 at 12:11 UTC
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.	[reply] [d/l] [select]