求pi

参考自：https://www.zhihu.com/question/402311979
由

$$\frac{{\pi }^4}{90}=\sum _{n=1}^{\mathrm{\infty }}\frac{1}{n^4}$$

得到：

$$\pi =\sqrt[4]{(\sum _{n=1}^{\mathrm{\infty }}\frac{1}{n^4})\cdot 90}$$

import math as m

from tqdm import trange#进度条
#求pi
N=10000000
num = 0

# for i in range(N):
#     num += 1/((2*i+1)**2)
# pi=m.sqrt(num*8)    
# print(pi)

for i in trange(N):
    num += 1/((i+1)**4)
pi=m.pow(num*90,0.25)    
print(pi)