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. In Python2.6: >>> 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. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
