Here's something to ponder: ^.-0.0000000001 _23.0259j3.14159
Does J know something we don't know? Or is this something I don't know? Linda -----Original Message----- From: progroamming-boun...@forums.jsoftware.com [mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Linda Alvord Sent: Thursday, January 17, 2013 5:23 AM To: programm...@jsoftware.com Subject: Re: [Jprogramming] Hermitian from triangular Isn't the log of negative numbers indefined? This is a problem: %1&o.+0 _ %1&o.-0 _ This is nice! %1&o.%_ _ %1&o.%__ __ The csc is very small for negative numbers close to zero and very large for very small positive numbers. Linda -----Original Message----- From: programming-boun...@forums.jsoftware.com [mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Bo Jacoby Sennt: Thursday, January 17, 2013 3:37 AM To: programm...@jsoftware.com Subject: Re: [Jprogramming] Hermitian from triangular Henry, How is negative zero different from positive zero when taking the log? ^.%__ NB. log -0 __ ^.%_ NB. log +0 __ - Bo >________________________________ > Fra: Henry Rich <henryhr...@nc.rr.com> >Til: programm...@jsoftware.com >Sendt: 0:38 torsdag den 17. januar 2013 >Emne: Re: [Jprogramming] Hermitian from triangular > >Negative zero makes sense as a last vestige of gradual underflow; and anyway, it's well-behaved: it looks like 0 except when you take the log, reciprocal, or square root. In any normal computation, it goes away. In contrast, NaN messes up anything it touches. > >I think we've had negative 0 in J forever. If NaN is a data virus, -0 >is a virus that has been inserted into our DNA. > >Henry Rich > >On 1/16/2013 4:45 PM, Raul Miller wrote: >> On Wed, Jan 16, 2013 at 4:35 PM, Henry Rich <henryhr...@nc.rr.com> wrote: >>> Negative zero isn't a bug, it's a feature that numerical types, >>> especially William Kahan, wanted to get into IEEE-754 to help out >>> some things. I'm not expert enough to explain. >> >> Something similar could be said about NaN. >> >---------------------------------------------------------------------- >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 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
