Hi Chris, 2017-01-12 13:17 GMT+01:00 Chris Angelico <ros...@gmail.com>: > > Most of the time one of my students talks to me about decimal vs > binary, they're thinking that a decimal literal (or converting the > default non-integer literal to be decimal) is a panacea to the "0.1 + > 0.2 != 0.3" problem.
Indeed. Decimal also doesn't solve the 1/3 issue. I don't understand why people always talk about Decimal, if you want math to work "right" you probably want fractions. (With the understanding that this is for still limited value of "right".) > Perhaps the real solution is a written-up > explanation of why binary floating point is actually a good thing, and > not just a backward-compatibility requirement? > I have sometimes considered writing up "Why the aliens of Epsilon Eridani, whose computers use 13-valued logic, still use floating point numbers with base 2." (Short overview: analysis form first principles shows that the base should be: 1. an integral number > 1 and 2. as small as possible (to minmax the relative rounding error)) The list of candidate bases satisfying these criteria is: 2. Stephan > > ChrisA > _______________________________________________ > Python-ideas mailing list > Python-ideas@python.org > https://mail.python.org/mailman/listinfo/python-ideas > Code of Conduct: http://python.org/psf/codeofconduct/ >
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