Having a loop issue-CodePudding

I am running the following code for pi value to calculate the first value which yields 3.14. I used manual values for range which works, but I want the values to be incremental to give me the first value. My code has a loop, and I know its a minor fix.

sum = 0
denominator = 1
counter = 1

while '3.14' not in str(sum):
    for i in range(counter):
        print(counter)
        if i % 2 == 0:
            sum  = 4/denominator
        else:
            sum -= 4/denominator
        denominator  = 2
        if '3.14' in str(sum):
            print(f'The iteration is {i 1} and the values is {sum}')
            break
    counter  = 1

CodePudding user response：

So it looks like you're trying to find the value of π by using the Leibniz equation, π/4 = 1 - 1/3 1/5 - 1/7

Oh, and don't name variables sum. It's an important built-in function.

import itertools

total = 0
# denominator will take the values 1, 3, 5, 7, 9, ...
for denominator in itertools.count(1, 2):
    if denominator % 4 == 1:
        total  = 4 / denominator
    else:
        total -= 4 / denominator
    if 3.14 <= total < 3.15:
        return denominator

CodePudding user response：

@Frank Yellin

Thank you for the response. Could you modify my existing code, so that I know where exactly the loop lies? My code works for manual values, like if I were to enter a manual range, say 200, it stops the iteration at 119. I want to use the counter logic in incremental fashion.

CodePudding user response：

There were two errors actually.

You have to subtract at even places and add at odd. So that had to be reversed.

There was no need of a second for loop. The first while is enough. It can be solved by the integer method but since you used the string method the refined code should be:

sum = 0
denominator = 1
counter = 1
#this is the main loop
while '3.14' not in str(sum):
    #print(counter)
    if counter % 2 != 0:
        sum  = 4/denominator
        print('sum=', sum)
    else:
        sum -= 4/denominator
    denominator  = 2
    if '3.14' in str(sum):
        print(f'The iteration is {counter 1} and the values is {sum}')
        break
    counter  = 1