[Python-3000] PEP 31XX: A Type Hierarchy for Numbers (and other algebraic entities) (original) (raw)

Guido van Rossum guido at python.org
Fri Apr 27 16:14:16 CEST 2007

On 4/27/07, Jan Grant <jan.grant at bristol.ac.uk> wrote:

On Thu, 26 Apr 2007, Dan Christensen wrote:

> Note also that double-precision reals are a subset of the rationals, > since each double precision real is exactly representable as a > rational number, but many rational numbers are not exactly > representable as double precision reals. Not sure if this means > that reals should be a subclass of the rationals. Not quite all: the space of doubles include a small number of things that aren't representable by a rational (+/- inf, for instance).

This suddenly makes me think of a new idea -- perhaps we could changes the type of Inf and NaNs to some other numeric type? We could then reserve a place in the numeric hierarchy for its abstract base class. Though I don't know if this extends to complex numbers with one or both parts NaN/Inf or not.

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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