My Code :
import math
def CalPI(precision):
answer = round((math.pi),precision)
return answer
precision=raw_input('Enter number of digits you want after decimal:')
try:
roundTo=int(precision)
print CalPI(roundTo)
except:
print 'Error'
When I run this code I get the output max only upto 11 decimal places. However I want to generate the output according to the input given by user.
Can anyone tell me where I am going wrong?
Thank you in advance!
If you use repr in your print you'll have 15 digits: 3.141592653589793.
If you want more digits (until 50) use
nb_digits = 40
print(format(math.pi, '.%dg' % nb_digits))
(thanks Stefan for the precision :) but as he stated again: don't trust digits after digit 15 so the 1000 digit program is the best).
For even more digits, compute pi yourself just like here:
"""
Math provides fast square rooting
Decimal gives the Decimal data type which is much better than Float
sys is needed to set the depth for recursion.
"""
from __future__ import print_function
import math, sys
from decimal import *
getcontext().rounding = ROUND_FLOOR
sys.setrecursionlimit(100000)
python2 = sys.version_info[0] == 2
if python2:
input = raw_input()
def factorial(n):
"""
Return the Factorial of a number using recursion
Parameters:
n -- Number to get factorial of
"""
if not n:
return 1
return n*factorial(n-1)
def getIteratedValue(k):
"""
Return the Iterations as given in the Chudnovsky Algorithm.
k iterations give k-1 decimal places. Since we need k decimal places
make iterations equal to k+1
Parameters:
k -- Number of Decimal Digits to get
"""
k = k+1
getcontext().prec = k
sum=0
for k in range(k):
first = factorial(6*k)*(13591409+545140134*k)
down = factorial(3*k)*(factorial(k))**3*(640320**(3*k))
sum += first/down
return Decimal(sum)
def getValueOfPi(k):
"""
Returns the calculated value of Pi using the iterated value of the loop
and some division as given in the Chudnovsky Algorithm
Parameters:
k -- Number of Decimal Digits upto which the value of Pi should be calculated
"""
iter = getIteratedValue(k)
up = 426880*math.sqrt(10005)
pi = Decimal(up)/iter
return pi
def shell():
"""
Console Function to create the interactive Shell.
Runs only when __name__ == __main__ that is when the script is being called directly
No return value and Parameters
"""
print ("Welcome to Pi Calculator. In the shell below Enter the number of digits upto which the value of Pi should be calculated or enter quit to exit")
while True:
print (">>> ", end='')
entry = input()
if entry == "quit":
break
if not entry.isdigit():
print ("You did not enter a number. Try again")
else:
print (getValueOfPi(int(entry)))
if __name__=='__main__':
shell()
