Vasudev Ram: A Pythonic ratio for pi (or, Py for pi :)

By Vasudev Ram

Py

Pi image attribution

A python built-in method can be used to find a ratio (of two integers) that equals the mathematical constant pi . [1]

This is how:

from __future__ import print_function

Doing:

dir(0.0) # or dir(float)

gives (some lines truncated):

'__str__', '__sub__', '__subclasshook__', '__truediv__', '__trunc__', 'as_integer_ratio', 'conjugate', 'fromhex', 'hex', 'imag', 'is_integer', 'real'] >>>

from which we see that as_integer_ratio is a method of float objects. (Floats are objects, so they can have methods.) So:

>>> import math >>> tup = math.pi.as_integer_ratio() >>> tup (884279719003555, 281474976710656) >>> tup[0] / tup[1] 3.141592653589793 >>> print(sys.version) 3.6.0a2 (v3.6.0a2:378893423552, Jun 14 2016, 01:21:40) [MSC v.1900 64 bit (AMD64 )] >>>

I was using Python 3.6 above . If you do this in Python 2.7 , the " / " causes integer division (when used with integers). So you have to multiply by a float to cause float division to happen:

>>> print(sys.version) 2.7.11 (v2.7.11:6d1b6a68f775, Dec 5 2015, 20:40:30) [MSC v.1500 64 bit (AMD64)] >>> tup[0] / tup[1] 3L >>> 1.0 * tup[0] / tup[1] 3.141592653589793 >>> [1] There are many Wikipedia topics related to pi .

Also check out a few of my earlier math-related posts (including the one titled "Bhaskaracharya and the man who found zero" :)

The second post in the series on the uses of randomness will be posted in a couple of days - sorry for the delay.

- Vasudev Ram - Online Python training and consulting Signup to hear about my new courses and products.