前天是3月14日，π日，想起以前写下的一个计算π值的Python代码，分享一下。The day before yesterday was March 14, π day, share a python code written before.

Python代码如下：
python source code as follows:

import sys
k, a, b, a1, b1 = 2, 4, 1, 12, 4
while 1==1:
  p, q, k = k*k, 2*k+1, k+1
  a, b, a1, b1 = a1, b1, p*a+q*a1, p*b+q*b1
  d = a // b
  d1 = a1 // b1
  while d == d1:
    sys.stdout.write(str(d))
    sys.stdout.flush()
    a, a1 = 10*(a%b), 10*(a1%b1)
    d, d1 = a//b, a1//b1

运行后会在屏幕上直接打印出π值。代码短小精悍，因为python自身支持大数运算。
python2和python3下都可以运行。
run it will print out the π value on the screen.code is short because python supports Big Number.
It can run on Python2 and python3