Ah. Thanks. (I haven’t had my coffee yet) ;-) It would be interesting to know if that really is more efficient.
> On Aug 3, 2017, at 9:33 AM, Greg Dove <greg.d...@gmail.com> wrote: > > I assume it is if (unknownNumOrNaN != unknownNumOrNaN ) > > I have used things like if (unknownNumOrNaN *0 !=0) in the past but the > above seems better > > > On Thu, Aug 3, 2017 at 6:20 PM, Harbs <harbs.li...@gmail.com> wrote: > >> 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) >>>>>>>> >>>>>>>> >>>>>> >>>>> >>>> >>>> >> >>
