# -*-coding:UTF-8-*- from itertools import * def pi(N): ''' 计算圆周率 :param N :return: pi ''' # step 1: 创建一个奇数序列: 1, 1+2, 1+2*2, ... odd = count(1, 2) # step 2: 取该序列的前N项: 1, 3, 5, 7, 9, ..., 2*N-1. odd_N = takewhile(lambda x: x <= 2 * N - 1, odd) # step 3: 添加正负符号并用4除: 4/1, -4/3, 4/5, -4/7, 4/9, ... sign = -1.0 sum = 0.0 for i,v in enumerate(odd_N,1): sign *= -1.0 sum += sign * (4 / v) # step 4: 求和 # print(f'No.{i}:{v} --> pi = {sum}') return sum if __name__ == '__main__': # pi(10) # 测试: print(pi(10)) print(pi(100)) print(pi(1000)) print(pi(10000)) assert 3.04 < pi(10) < 3.05 assert 3.13 < pi(100) < 3.14 assert 3.140 < pi(1000) < 3.141 assert 3.1414 < pi(10000) < 3.1415 print('ok')
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