快Math.exp（）通过JNI？ [英] faster Math.exp() via JNI?

问题描述

我需要计算 Math.exp（）从Java非常频繁，是有可能得到本机的版本比运行速度更快的的Java 的 Math.exp（） ??

I need to calculate Math.exp() from java very frequently, is it possible to get a native version to run faster than java's Math.exp()??

我尝试了JNI + C，但它比只是普通的的Java

I tried just jni + C, but it's slower than just plain java.

推荐答案

+1来编写自己的EXP（）实现。也就是说，如果这是的真正的一个瓶颈在应用程序中。如果你能处理一点点不准确，有一些非常有效的指数估计算法在那里，他们中的一些可以追溯到几个世纪。据我了解，Java的EXP（）的实现是相当缓慢的，即使它必须返回精确的结果算法。

+1 to writing your own exp() implementation. That is, if this is really a bottle-neck in your application. If you can deal with a little inaccuracy, there are a number of extremely efficient exponent estimation algorithms out there, some of them dating back centuries. As I understand it, Java's exp() implementation is fairly slow, even for algorithms which must return "exact" results.

哦，不要害怕写在纯Java的EXP（）实现。 JNI有很大的开销，和JVM能够优化运行时字节code有时甚至超越了C / C ++是能实现的。

Oh, and don't be afraid to write that exp() implementation in pure-Java. JNI has a lot of overhead, and the JVM is able to optimize bytecode at runtime sometimes even beyond what C/C++ is able to achieve.

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