파이썬에서 π를 입력하는 방법

import sys
import math
  
defmain(argv):  
    if len(argv) !=1:
        sys.exit(&#39;Usage: calc_pi.py <n>&#39;)  
    print&#39;\nComputing Pi v.01\n&#39;
      
    a=1.0
    b=1.0/math.sqrt(2)
    t=1.0/4.0
    p=1.0
          
    for i in range(int(sys.argv[1])):
        at=(a+b)/2
        bt=math.sqrt(a*b)
        tt=t-p*(a-at)**2
        pt=2*p          
        a=at;b=bt;t=tt;p=pt          
    my_pi=(a+b)**2/(4*t)
    accuracy=100*(math.pi-my_pi)/my_pi
          
    print"Pi is approximately: "+str(my_pi)
    print"Accuracy with math.pi: "+str(accuracy)
      
if__name__=="__main__":
    main(sys.argv[1:])