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From: Ben Finney <ben+python@benfinney.id.au>
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Subject: Re: Float
Date: Fri, 29 Jul 2016 20:25:29 +1000
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Xref: csiph.com comp.lang.python:112011

Cai Gengyang <gengyangcai@gmail.com> writes:

> Can someone explain in layman's terms what "float" means ?

They are a compromise: in a known number of bits and with explict
very-fast hardware support, represent numbers at a large range of
scales. The compromise is that the values have limited precision for
representing those numbers.

<URL:https://en.wikipedia.org/wiki/Floating_point>

If you want exact representations of numbers, you don't want
floating-point numbers; you want Fraction or Decimal or integer etc.

If you just want to have fairly-good precision of fractional numbers, as
fast as your computer can compute them, then maybe the built-in
floating-point numbers are what you want.

There is no substitute for knowing the characteristics of floating-point
numbers, and using that information to decide when they are appropriate
and when they are not.

-- 
 \     “Books and opinions, no matter from whom they came, if they are |
  `\     in opposition to human rights, are nothing but dead letters.” |
_o__)                                                  —Ernestine Rose |
Ben Finney