There are ways it could be more fulfilling. With (-)(QNaN1, QNaN2) and with (/), Julia appears to propogate the one on the left, QNaN1. The situation with (+) an (*) is more opaque and I'll assume that has to do with Julia's deep preservation of commutivity. As I understand it, the intent is to pick up useful, localized situational reporting (e.g. the intensity of activity over some model-trust sub-region or to obtain a more direct read of the structural stress on the cross members of a bridge by getting information from within bolts as the computer modelling and analysis continues. If it were to be done, we tell them where to start and when to stay. When they have gathered something, the move on by proaogating through the numerical computation.The aquired payloads would serve as a sketch of detail from the internals of computational terrain.
IEEE 754-2008 makes it clear that QNaN payload values are fare game: (is says details of NaN propagtion may have vender differences, and) "The following value-changing transformations, among others, preserve the literal meaning of the source code: .. ― Changing the payload or sign bit of a quiet NaN." Graspable, in my estimation, with instructable, or at least disciplined and non-contrarian NaN propogators. On Monday, August 3, 2015 at 3:58:37 PM UTC-4, Jeffrey Sarnoff wrote: > > > Jason, > If the software or circuitry is IEEE 758-2008 compliant, all those quiet > NaNs are usable. Most vendors select one or two of them (for quiet 64bit > nans, usually 0x7ff8000000000000 and/or 0xfff8000000000000) and do > everything NaN related with, say, those two. I hope vendors are not saying > they have a Standards complying product when that is untrue. > About compliance and NaNs, my impression is "you don`t have to use them, > but they are expected to be present." > They may play by different rules. > > Stuart, > The horse and arriage similie for a quiet nan makes sense to me. > Travelling in unfamiliar places, occasionally noticing something of > interest .. or getting a reminder .. and gathering some small, revealing > information to place it in the carriage knowing that and it will arrive > with me when the horse returns home. As I read it (his paper, not my > redaction), William Kahan expressed an abiding regard for the efficacy and > utillity of quiet NaNs as a numerical software engineers' participatory > tool. That's what prompted me to to write the module. > > Thank you both for the thoughts. > > > > > > > On Monday, August 3, 2015 at 12:56:57 PM UTC-4, Jason Riedy wrote: >> >> And Jeffrey Sarnoff writes: >> > AFAIK Julia and most other languages use one or two of each in >> > most circumstances. >> >> And many chips produce only one, the platform's "canonical" NaN. >> Some pass one of the argument NaNs through but rarely will >> specify which. >> >>
