def pi(N): ' 计算pi的值 ' _odd=itertools.count(1,2) # step 1: 创建一个奇数序列: 1, 3, 5, 7, 9, ... n_odd=itertools.takewhile(lambda x:x<=2*N-1,_odd) # step 2: 取该序列的前N项: 1, 3, 5, 7, 9, ..., 2*N-1. lst=[(-1)**((n+1)/2+1)*4/n for n in n_odd] # step 3: 添加正负符号并用4除: 4/1, -4/3, 4/5, -4/7, 4/9, ...@@列表推导式 p=sum(lst) # step 4: 求和:@@这一行可以不要,return sum(lst) return p
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Champhy_Who