python3.8 丘德诺夫斯基（Chudnovsky）计算高精度圆

#!/usr/bin/python3
import time
def Sqrt10005():  # Sqrt(10005L) by Imitate-Manual Method
    n1 = 0
    c = 10002499687  # 100.02499687
    mc = 8;
    m = mc
    f1 = 10 ** mc
    f2 = f1 * f1
    a = 10005 * f2 - c * c
    while mc < n:
        a *= f2
        b = c * 2 * f1
        d = a // b
        c = c * f1 + d
        a -= d * (b + d)
        mc += m
        if mc * 2 > n:
            m = n - mc
        else:
            m = mc
        f1 = 10 ** m
        f2 = f1 * f1
        n1 += 1
    return c


# Main Program
#
print("Chudnovsky法計算高精度圓周率程序")
while 1:
    n = int(input('計算位數[1..50000],0:退出：'))
    if n <= 10: break
    n += 2
    base = 10 ** n
    t = time.perf_counter()
    # Start Calculating
    A = 13591409 * base;
    B = A
    c3 = 13591409
    i = 1
    while abs(A) > 5:
        c1 = ((108 - 72 * i) * i - 46) * i + 5
        c2 = 10939058860032000 * i ** 3
        c4 = c3;
        c3 += 545140134
        i += 1
        A = A * c1 * c3 // (c2 * c4)  # Must in form: A=A*...
        B += A
    p = 426880 * base * Sqrt10005() // B // 100
    # Post access
    print("用時= %8.3f 秒" % (time.perf_counter() - t))
    s = input('是否显示结果(Y/N):')
    if (s == 'Y') | (s == "y"): print("PI=" + str(p))
# end