Check if a number is rational in Python, for a given fp accuracy

Question

I would like to know a good way of checking if a number x is a rational (two integers n,m exist so that x=n/m) in python.

In Mathematica, this is done by the functio

Answer 1

Any number with a finite decimal expansion is a rational number. You could always solve for instance

5.195181354985216

by saying that it corresponds to

5195181354985216 / 1000000000000000

So since floats and doubles have finite precision they're all rationals.