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月半意

#1 Created at ... [Delete] [Delete and Lock User]
def pi(N):
        
    ' 计算pi的值 '
    # step 1: 创建一个奇数序列: 1, 3, 5, 7, 9, ...
    odd = itertools.count(1,2)
    # step 2: 取该序列的前N项: 1, 3, 5, 7, 9, ..., 2*N-1.
    natuals = itertools.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, ...
    # step 4: 求和:
    result = 0
    i = 0
    for x in natuals:
        result += 4/x * pow(-1,i)
        i += 1
    return result

月半意

#2 Created at ... [Delete] [Delete and Lock User]
from functools import reduce
def pi(N):
        
    ' 计算pi的值 '
    # step 1: 创建一个奇数序列: 1, 3, 5, 7, 9, ...
    odd = itertools.count(1,2)
    # step 2: 取该序列的前N项: 1, 3, 5, 7, 9, ..., 2*N-1.
    natuals = itertools.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, ...
    # step 4: 求和:
    result = reduce(lambda x:(-1)**round(x%4/4)*4/x,natuals)
    return result

这样写为什么报错啊:TypeError: <lambda>() takes 1 positional argument but 2 were given

BigPistachio

#3 Created at ... [Delete] [Delete and Lock User]

因为reduce函数是求和啊,而你只对单个元素进行操作了,

result = reduce(lambda x, y:(-1)**round(x%4/4)*4/x + (-1)**round(y%4/4)*4/y, natuals)

酱紫就好了呀


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