pi计算中的分段错误（python）(segmentation fault in pi calculation (python))

pi计算中的分段错误（python）(segmentation fault in pi calculation (python)) def pi(times): seq = [] counter = 0 for x in range(times): counter += 2 seq.append("((%f**2)/(%f*%f))*"%(float(counter), float(counter-1), float(counter+1))) seq.append("1.0") seq = "".join(seq) seq = eval(seq) return seq*2

任何地方超过85000的条款，我得到一个分割错误和python退出。 我怎样才能避免这种情况？ 它为什么会崩溃？ 不能只是请使用更多的内存或什么？

def pi(times): seq = [] counter = 0 for x in range(times): counter += 2 seq.append("((%f**2)/(%f*%f))*"%(float(counter), float(counter-1), float(counter+1))) seq.append("1.0") seq = "".join(seq) seq = eval(seq) return seq*2

Anywhere past 85000 terms I get a segmentation fault and python quits. How can I avoid this? Why is it crashing? Can't it just please use more memory or something?

最满意答案

您似乎在eval中发现了一个无法处理疯狂长表达式的错误：

>>> eval("1.0*"*10000+"1.0") 1.0 >>> eval("1.0*"*100000+"1.0") # segfault here

不过，我尽量使用“疯狂地长”这个词。 不要这样做，随着时间的推移计算碎片。 在这种情况下没有理由使用eval 。

You appear to have found a bug in eval where it can't handle insanely long expressions:

>>> eval("1.0*"*10000+"1.0") 1.0 >>> eval("1.0*"*100000+"1.0") # segfault here

I use the phrase "insanely long" advisedly though. Don't do it that way, calculate the pieces as you go. There is no reason to be using eval in this situation.