Henry, How is negative zero different from positive zero when taking the log? ^.%__ NB. log -0 __ ^.%_ NB. log +0 __
- Bo >________________________________ > Fra: Henry Rich <[email protected]> >Til: [email protected] >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 <[email protected]> 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
