Implementation limitations of float.as_integer_ratio()

Question

Recently, a correspondent mentioned float.as_integer_ratio(), new in Python 2.6, noting that typical floating point implementations are essentially rational approximations o

Answer 1

You get better approximations using

fractions.Fraction.from_float(math.pi).limit_denominator()

Fractions are included since maybe version 3.0. However, math.pi doesn't have enough accuracy to return a 30 digit approximation.