What exactly is "exact" (was Clean Singleton Docstrings)

[Ian Kelly]

On Mon, Jul 18, 2016 at 3:29 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Monday 18 July 2016 14:16, Rustom Mody wrote:
>> In short one could think of inexact and exact — in scheme's intended
>> semantics — as better called scientific (or science-ic) and mathematic
>> numbers.
>
> I don't think so. "Science" uses both experimentally-derived numbers (e.g. G,
> c, the mass of the electron) and numbers known exactly (√2, e, π).

Off-topic, c being a fundamental constant is actually in the latter
category. Its *exact* value is 299792458 m/s.

The length of the meter, on the other hand, is defined as the distance
traveled by light in a vacuum in 1/299792458 seconds and is subject to
the precision of measurements.