1 o. y and other similar periodic functions signal limit error when y exceeds a certain theta. Thus:
1 o. 1e9 |limit error | 1 o.1000000000 1 o. _ is more of the same. For finite x and y, the dictionary defines x|y as y-x*<.y%x+0=x . This device is as good (or as bad) as any other to make sense of the cases when x or y are infinite. Accordingly: res=: 4 : 'y-x*<.y%x+0=x' 10 res _ |NaN error: res | y -x*<.y%x+0=x _ res __ |NaN error: res | y-x*<.y %x+0=x Basically, 10|_ founders on doing _-_ , and _|__ founders on __%_ . Thank you and congratulations for being the first successful hunter in the treasure hunt. ----- Original Message ----- From: Henry Rich <[EMAIL PROTECTED]> Date: Monday, February 25, 2008 2:34 Subject: RE: [Jbeta] Use of the name 'NaN' deprecated To: 'Beta forum' <[email protected]> > One can argue that more information is better than less; or > one can argue that implementation detail should be kept > private. I prefer the latter. Maybe it's a matter of > taste. > > I can't see the reason for a distinction between the > following two errors: > > _ - _ > |NaN error > 1 o. _ > |limit error > > except that the first is a _. that the hardware generates, > while the second _. is detected in software. They're both > domain errors because the proper result is _. . When you > introduce 'NaN error', aren't you giving yourself the > additional burden of having to decide which errors it > most precisely describes? > > Just nosing around, what about this: > > 10 | _ > 0 > > shouldn't this be a NaN error? > > _ | __ > __ > > shouldn't this be a NaN error? At the least, shouldn't > the result be positive? > > Henry Rich > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Roger Hui > > Sent: Monday, February 25, 2008 1:04 AM > > To: Beta forum > > Subject: Re: [Jbeta] Use of the name 'NaN' deprecated > > > > > Do change 'NaN error' to either 'domain error' (preferred) > > or '_. error' . > > > > It is advantageous to have a message for "NaN error" > > distinct from "domain error", so that when you get > > one of them you don't have to puzzle over what kind > > of domain error it was. In a sense they are all domain > > errors, but it is helpful to have "rank error", "index error", etc. > > and now "NaN error". > > > > As for the exact spelling of the message, you can change > > it to whatever you like via 9!:9 . > > > > > > > > ----- Original Message ----- > > From: Henry Rich <[EMAIL PROTECTED]> > > Date: Sunday, February 24, 2008 9:40 > > Subject: RE: [Jbeta] Use of the name 'NaN' deprecated > > To: 'Beta forum' <[email protected]> > > > > > I think you are replying to a different argument than the > > > one I was trying to make. > > > > > > I wasn't suggesting that _. be 'above that' in the sense of > > > following certain J-defined rules independent of the > > > IEEE spec. That would be OK but if it's too hard, > > > let it go. > > > > > > I am happy with all the implementation decisions you have made. > > > I am particularly happy with raising error when _. would > > > be created. > > > > > > My only objection is to using the name 'NaN'. Maybe > you use > > > a NaN for _., but I see no reason to pollute the documentation > > > with that term. I AM suggesting that the language spec be > > > 'above that', because NaN is a new and unnecessary concept > > > within J numbers. > > > > > > And _. IS a number. qbeta tells me so: > > > > > > 9!:14'' > > > j602/beta/2008-02-22/22:30 > > > 3!:0 (_.) > > > 8 > > > > > > Don't change a line of code. Do change the doc of > 128!:5 > > > to say > > > it checks for the presence of _. rather than of NaN. > Do change > > > 'NaN error' to either 'domain error' (preferred) or '_. > error' . > > > > > > The only appearance of NaN in the docs should be the one in _., > > > which is > > > > > > The indeterminate _. is provided to aid in > dealing with > > > NaN (not a number) in data from external sources... > > > > > > This makes clear that NaN is IEEE, not J. Occam's razor. > > > > > > Henry Rich ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
