如何将Python除以-0.0和0.0分别导致-Inf和Inf? [英] How to get Python division by -0.0 and 0.0 to result in -Inf and Inf, respectively?

问题描述

我遇到的情况是合理的除以0.0或除以-0.0，我希望分别看到+ Inf和-Inf作为结果.看来Python很喜欢抛出

I have a situation where it is reasonable to have a division by 0.0 or by -0.0 where I would expect to see +Inf and -Inf, respectively, as results. It seems that Python enjoys throwing a

ZeroDivisionError: float division by zero

在任何情况下

.显然，我认为我可以将其封装为0.0来进行测试.但是，我找不到区分+0.0和-0.0的方法. (仅供参考，您可以通过输入-0.0或通过常见的计算方式(例如-1.0 * 0.0)轻松获得-0.0.

in either case. Obviously, I figured that I could simply wrap this with a test for 0.0. However, I can't find a way to distinguish between +0.0 and -0.0. (FYI you can easily get a -0.0 by typing it or via common calculations such as -1.0 * 0.0).

IEEE可以很好地处理所有这些问题，但是Python似乎很努力地隐藏经过深思熟虑的IEEE行为.实际上，0.0 == -0.0实际上是IEEE的功能，因此Python的行为会严重破坏事情.它可以在C，Java，Tcl甚至JavaScript上完美运行.

IEEE handles this all very nicely, but Python seems to take pains to hide the well thought out IEEE behavior. In fact, the fact that 0.0 == -0.0 is actually an IEEE feature so Python's behavior seriously breaks things. It works perfectly well in C, Java, Tcl, and even JavaScript.

建议?

推荐答案

from math import copysign

def divide(numerator, denominator):
    if denominator == 0.0:
        return copysign(float('inf'), denominator)
    return numerator / denominator

>>> divide(1, -0.0)
-inf
>>> divide(1, 0)
inf

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