off topic but please forgive me me and answer
steve at REMOVE-THIS-cybersource.com.au
Sat Apr 3 01:07:53 CEST 2010
On Fri, 02 Apr 2010 12:35:55 -0700, Mensanator wrote:
>> If you want an exact result when multiplying arbitrary fractions, you
>> need to avoid floats and decimals and use Fractions:
>> >>> Fraction(1, 2)**2
>> Fraction(1, 4)
> Where do you get that from?
Where do I get what from? Fraction? Oops, sorry about that.
>>> from fractions import Fraction
In older Pythons, there was a demo module Demo/classes/Rat.py but it may
not be installed on your system. See http://bugs.python.org/issue1682
If you meant, where did I get the statement about exact results from,
both float and Decimal are fixed precision numbers. float precision is
fixed by the operating system and/or hardware; Decimal precision can be
arbitrarily chosen by the caller, but having made that choice,
calculations are rounded to that precision. Only Fraction gives exact
results for any arbitrary rational number.
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