How about adding rational fraction to Python?

[Gabriel Genellina]

En Tue, 04 Mar 2008 11:46:48 -0200, NickC <ncoghlan at gmail.com> escribi�:

> A mildly interesting Py3k experiment:
>
> Python 3.0a3+ (py3k:61229, Mar  4 2008, 21:38:15)
> [GCC 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
>>>> from fractions import Fraction
>>>> from decimal import Decimal
>>>> def check_accuracy(num_type, max_val=1000):
> ...     wrong = 0
> ...     for x in range(1, max_val):
> ...         for y in range(1, max_val):
> ...             wrong += (x / num_type(y)) * y != x
> ...     return wrong
> ...
>>>> check_accuracy(float)
> 101502
>>>> check_accuracy(Decimal)
> 310013
>>>> check_accuracy(Fraction)
> 0
>
>
> The conclusions I came to based on running that experiment are:
> - Decimal actually appears to suffer more rounding problems than float
> for rational arithmetic

Mmm, but I doubt that counting how many times the results are equal, is  
the right way to evaluate "accuracy".
A stopped clock shows the right time twice a day; a clock that loses one  
minute per day shows the right time once every two years. Clearly the  
stopped clock is much better!
http://mybanyantree.wordpress.com/category/lewis-carrol/

-- 
Gabriel Genellina