On Mon, May 23, 2016 at 8:29 AM, Ben Bacarisse <ben.use...@bsb.me.uk> wrote: > Ian Kelly <ian.g.ke...@gmail.com> writes: > >> On Mon, May 23, 2016 at 2:09 AM, Steven D'Aprano >> <steve+comp.lang.pyt...@pearwood.info> wrote: >>> Are you saying that the Egyptians, Babylonians and Greeks didn't know how to >>> work with fractions? >>> >>> http://mathworld.wolfram.com/EgyptianFraction.html >>> >>> http://nrich.maths.org/2515 >>> >>> Okay, it's not quite 4000 years ago. Sometimes my historical sense of the >>> distant past is a tad inaccurate. Shall we say 2000 years instead? >> >> Those links give dates of 1650 BC and 1800 BC respectively, so I'd say >> your initial guess was closer. > > Right, but this is to miss the point. Let's say that 4000 years have > defined 1/3 to be one third, but Python 3 (as do many programming > languages) defines 1/3 to be something very very very very close to one > third, and *that* idea is very very very very new! It's unfortunate > that the example in this thread does not illustrate the main problem of > shifting to binary floating point, because 1/2 happens to be exactly > representable.
I'm not going to dig back through the thread, but my recollection is that's exactly why that example was chosen. Since 1/2 can be represented exactly as a float, it *should* be represented as a float. Picking another value (0) that isn't even close to the exact value of 1/2 isn't helping anybody. -- https://mail.python.org/mailman/listinfo/python-list
