[Edu-sig] Long floats?

[Daniel Yoo]

On Wed, 10 Jan 2001, Kirby Urner wrote:

> Here's something from a math teacher who hangs out on math-teach
> (where I've been cross-posting a few of my "math through 
> programming" essays).
> 
> He wonders if there's a way to get "long floats".  I don't 
> think there is, except maybe there's an add-on module I don't
> know about.  Any clues?

According to the documentation at:

    http://python.org/doc/current/lib/module-mpz.html

there should be a rational numbers module in one of the Demos directories
(Demo/classes/Rat.py).  Here's an interpreter session that plays a little
bit with it.

###
>>> from Rat import rat
>>> rat(5,3)
Rat(5,3)
>>> str(rat(1,3))
'(1/3)'
>>> 1000-.0001
999.99990000000003
>>> rat(1000) - rat(.0001)
999.99990000000003                 # whoops!
>>> rat(1000) - rat(1, 1000) 
Rat(999999,1000)                   # ah, that's better.
###

Hope this helps!