Bo wrote: > Devon, your solution > 9!:19]1e_11 This was not intended as a solution but a demonstration that +. is sensitive to comparison tolerance. "9!:19" sets comparison tolerance but does not allow an argument greater than 1e_11.
On Sat, May 16, 2020 at 11:25 AM Raul Miller <rauldmil...@gmail.com> wrote: > In an expression like > > +./&.:(1p1&*)12 30 > 6 > > we should note that 12 and 30 are both [small] integers (and, thus, exact). > > Also, 1p1 is a value close to pi, and while it's true that it's not > exactly pi, it's a common factor in this context. So it comes through > in the gcd result. > > Basically it's just an arbitrary value which has an exact > representation (which is all that matters in this context). > > Thanks, > > -- > Raul > > > > > > > On Sat, May 16, 2020 at 8:24 AM 'Bo Jacoby' via Programming > <programm...@jsoftware.com> wrote: > > > > Raul, note that this works: > > > > (+.&.(*&1p1))/2 3 > > > > 1 > > > > > > > > even though the numbers > > > > 0j16":(*&1p1)2 3 > > > > 6.2831853071795862 9.4247779607693793 > > > > do not satisfy your demands of being exactly represented. > > Thanks! > > Bo > > > > > > > > > > Den lørdag den 16. maj 2020 13.03.21 CEST skrev Hauke Rehr < > hauke.r...@uni-jena.de>: > > > > The answer 3j2 looks sane. > > 3j2 * 0j1 0j_1 > > and the only one in the first quadrant. > > Nice! > > > > Am 16.05.20 um 12:32 schrieb Raul Miller: > > > Oh, I see -- or, I think I see what you were trying to illustrate now. > > > > > > That said, this is kind of interesting: > > > +./(,-)2j_3 > > > 3j2 > > > > > > But I also noticed that +/(,-) seems to bring back associativity (we > > > already had commutativity with +.): > > > > > > (i.6) A."0 1]4.57 4.34 4.44 > > > 4.57 4.34 4.44 > > > 4.57 4.44 4.34 > > > 4.34 4.57 4.44 > > > 4.34 4.44 4.57 > > > 4.44 4.57 4.34 > > > 4.44 4.34 4.57 > > > +./@(,-)"1 (i.6) A."0 1]4.57 4.34 4.44 > > > 8.88178e_16 8.88178e_16 8.88178e_16 8.88178e_16 8.88178e_16 8.88178e_16 > > > > > > Thanks, > > > > > > > > > -- > > > Raul > > > > > > On Sat, May 16, 2020 at 5:51 AM Hauke Rehr <hauke.r...@uni-jena.de> > wrote: > > >> > > >> sorry, I was not sufficiently precise about my example > > >> I meant to talk about atomic a only > > >> > > >> if $ a is empty, then > > >> +./ (, -) a > > >> will work > > >> > > >> Thanks for pointing out the lack of precision. > > >> > > >> Am 16.05.20 um 11:46 schrieb Raul Miller: > > >>> I was talking about the implementation. > > >>> > > >>> These are different results: > > >>> > > >>> +./@(,-)4.57 4.34 4.44 > > >>> 8.88178e_16 > > >>> +./@(,-)&.x:4.57 4.34 4.44 > > >>> 0.01 > > >>> +./@(,-)&.:(*&1p1)4.57 4.34 4.44 > > >>> 5.65432e_16 > > >>> > > >>> The reason is that binary floating point cannot represent 5^_1 nor > > >>> 5^_2 accurately. > > >>> > > >>> Thanks, > > >>> > > >> > > >> -- > > >> ---------------------- > > >> mail written using NEO > > >> neo-layout.org > > >> ---------------------------------------------------------------------- > > >> For information about J forums see > http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > > > For information about J forums see http://www.jsoftware.com/forums.htm > > > > > > > -- > > ---------------------- > > mail written using NEO > > neo-layout.org > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Devon McCormick, CFA Quantitative Consultant ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
