On Mon, Oct 14, 2002 at 08:25:43PM -0400, Mark J. Reed wrote: > On 2002-10-14 at 20:15:33, Michael G Schwern wrote: > > There are several verbal proofs why 1/0 is not +Infinity here: > > http://mathforum.org/dr.math/faq/faq.divideby0.html > > Yeah, that would be why I sent my followup. I did not mean to > imply that 1/0 is positive infinity in "real world math".
Sorry, I was a little too fast on the reply gun. > However, returning Infinity when asked to divide a finite > number by 0 is conformant behavior according to the IEEE spec. > An implementation is *allowed* to indicate an error on division > by 0, but is not *required* to - returning infinity is legal. <snip> > It is also, as an example, the behavior required by the ECMAScript > specification. Heh. "Because Javascript does it" is supposed to be an argument for? ;) > In any case, my point was simply that 1/0 is not NaN. If you're going to > return a defined value as the result of 1/0, you should return +Infinity > instead. Mathematically, 1/0 is not +Infinity. It's undefined/indeterminate in the set of rational numbers. The IEEE may say otherwise. So here's a big question. Should Perl's core maths conform to IEEE or mathematics? (Not something I expect an answer to.) > NaN is used for other purposes, such as square roots of negative > numbers when complex numbers are not available, or as the return value > of failed numeric coercions, or of operations where even as a limit the > result is indeterminate, such as 0/0. So NaN means "this equation might have an answer, just not in your current set of numbers" and it means "a coercion failed" and it means "the limit is indeterminate"? A lot of meanings. But it doesn't mean 1/0? This gets into questions of how Perl's math systems are extended/overridden. Something better suited to guys like Tels I guess. While I'd personally like built-in support for automatic bignum conversion, I suppose the best answer I could expect right now would be "Perl 6's support for additional maths will be greater than or equal to Perl 5". -- Michael G. Schwern <[EMAIL PROTECTED]> http://www.pobox.com/~schwern/ Perl Quality Assurance <[EMAIL PROTECTED]> Kwalitee Is Job One I'm a man, but I can change... if I have to. -- Red Green
