I’m curious. How does that work? unknownNumOrNaN != NaN will always be true
> On Aug 3, 2017, at 1:37 AM, Josh Tynjala <joshtynj...@gmail.com> wrote: > > Good one! To avoid the overhead of the isNaN() function call, I frequently > rely on the fact that NaN != NaN. > > - Josh > > On Wed, Aug 2, 2017 at 3:32 PM, Harbs <harbs.li...@gmail.com> wrote: > >> Thanks for the history lesson. :-) >> >> This does bring up another difference between an initialized value of NaN >> and undefined: >> >> NaN != NaN, while undefined == undefined >> >>> On Aug 3, 2017, at 1:00 AM, Dave Fisher <dave2w...@comcast.net> wrote: >>> >>> I hate this Macbook’s touch top bar which puts a send button directly >> above the delete key. >>> >>>> On Aug 2, 2017, at 2:50 PM, Dave Fisher <dave2w...@comcast.net> wrote: >>>> >>>> Hi Folks, >>>> >>>> A peanut gallery look at NaN which is really a bit encoding for various >> kinds of floating point number errors like underflow, overflow, divided by >> 0, etc. In my Fortran past life we used XMISS as a special valu >>> >>> Value. Essentially undefined. >>> >>> IEEE had very particular definitions and Apple published a book about >> SANE. >>> >>> At any rate what you guys are observing is by design: NaN always results >> in false in any comparison. And it is a number. But it is not a number in >> floating point so much as it is an error condition. >>> >>> https://stackoverflow.com/questions/1565164/what-is-the- >> rationale-for-all-comparisons-returning-false-for-ieee754-nan-values >>> >>> https://people.eecs.berkeley.edu/~wkahan/ieee754status/IEEE754.PDF >>> >>> My father complained about when the IBM 360 came out in the early 1960’s >> he had to go to doubles because the IBM architecture went from 6 - 6 bit >> words for a single to 4 - 8 bit words. The practical result was twice as >> much magnetic tape both length and number of reals. >>> >>> Regards, >>> Dave >>> >>>> >>>>> On Aug 1, 2017, at 3:21 PM, Greg Dove <greg.d...@gmail.com> wrote: >>>>> >>>>> Yes it does. NaN is an 'instance' of the Number type (even though it is >>>>> 'Not a Number' ;) ) >>>>> >>>>> >>>>> On Wed, Aug 2, 2017 at 10:18 AM, Harbs <harbs.li...@gmail.com> wrote: >>>>> >>>>>> Interesting. >>>>>> >>>>>> I’m not sure that I realized that NaN passes that test. Does it? >>>>>> >>>>>>> On Aug 2, 2017, at 1:12 AM, Greg Dove <greg.d...@gmail.com> wrote: >>>>>>> >>>>>>> I agree undefined works the same as NaN for many things for example, >> but >>>>>> it >>>>>>> fails on very basic things like if (x is Number) >>>>>> >>>>>> >>>> >>> >> >>
