No complex rationals in Python 3.0

Christian Heimes lists at
Mon Nov 24 20:31:39 CET 2008

Rock wrote:
> I appreciate the inclusion of the fractions module in Python 2.6 and
> therefore in Python 3.0. But I feel there's something missing: no
> possibility for complex rationals (or arbitrary precision) integers. I
> was just checking the complex number support in Python, compared, for
> instance, to Common Lisp and Scheme, and I realized that there was
> this subtle omission. The inclusion of rationals and arbitrary
> integers is cool, but the numeric tower (say, compared to Scheme) is
> not complete. I don't think there would be a performance hit if
> complex rationals were provided. Ordinary operations on complex
> floats, in theory, should not be affected and handled separately. But
> it would be nice to be able to do:
> (3/4 + 1/2j) * (1/4 - j) = 11/16 - 5/8j
> with no loss of precision.
> Python is heavily used in math and science all over the world. We've
> even got a recent symbolic math project (sympy) that looks very
> promising, so I guess this could be an important issue.

Nobody has submitted a PEP and patch to implement the feature in time. 
There is still Python 3.1, you know? If you like to contribute the 
feature then please start a discussion on the Python Ideas mailing list 
(not the developer lists!).

> Note: there exists a library that implements what I'm talking about:
> but still I personally would have liked to see this stuff included
> natively in the new Python 3.0.

The code depends on the CLN library which isn't suited for the Python 
core. It's written in C++ and it's licensed under GPL. Neither GPL nor 
LGPL software can't be integrated into the core. We also require all 
code to be compatible with C89.


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