x * x vs Math.pow（x，2）java性能 [英] x*x vs Math.pow(x,2) java performance

问题描述

我已经做过一些关于x * x或Math.pow（x，2）在Java中是否更快的测试。我期待简单的x * x有点快，但事实证明它的速度相当快。有人可以告诉我，请问这有什么可能吗？

I have done some testing about whether x * x or Math.pow(x,2) is faster in Java. I was expecting simple x * x to be somewhat faster, however, it turned out that its about equaly fast. Can someone enlighten me, how is that possible, please?

推荐答案

你知道它已被JIT（甚至已经编译 - 时间）同样的事情。这些微基准测试很少能提供非常有用的结果，因为没有真正的上下文。

For all you know it's JITted (or even already in compile-time) down to the same exact thing. These kinds of micro-benchmarks rarely give very usable results, since there is no real context.

这绝对不是偏爱另一个的理由，因为现实世界的代码很少有一个简单的 x ^ 2 操作作为性能热点。

It's definitely not a reason to prefer one over another, since real world code rarely has a simple x^2 operation as a performance hotspot.

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