在Java中将角度标准化为+/-π弧度的标准方法 [英] Standard way to normalize an angle to +/- π radians in Java

问题描述

在Java中是否存在库函数或众所周知的快速有效方法来将角度标准化为+/-π - 例如添加两个角度时？

Is there a library function or a well-known quick efficient way in Java to normalize an angle to +/- π — e.g. when adding two angles?

我现在得到了什么（基于这个回答）基本上是下面的代码......

What I've got now (based on this answer) is basically the code below...

private static final double TWO_PI = 2 * Math.PI;

double normalize(double theta) {
    double normalized = theta % TWO_PI;
    normalized = (normalized + TWO_PI) % TWO_PI;
    return normalized <= Math.PI ? normalized : normalized - TWO_PI;
}

...但它似乎有点复杂，性能方面我是对模运算符不感兴趣。 （注意，我不能保证 theta 不是一些相对较大的数字，所以我认为没有循环的纯加法/减法解决方案。我不知道实际上知道手动循环可能与％进行比较。）

...but it seems a little complicated and performance-wise I'm not excited about the modulo operator. (Note that I can't guarantee theta isn't some relatively large number, so I don't think there's a pure addition/subtraction solution without looping. I don't actually know how a hand-rolled loop is likely to compare to %.)

是否经过充分测试我可以使用优化的库函数，还是一个更好的算法，或者这样做得好吗？

Is there a well-tested optimized library function I can use, or a better algorithm, or is this as good as it gets?

推荐答案

Apache commons有一个：

Apache commons has one:

http://commons.apache.org/proper/commons-math/javadocs/api-3.6.1/org/ apache / commons / math3 / util / MathUtils.html＃normalizeAngle（double，double）

规范化-π之间的角度和+π

normalize an angle between -π and +π

a = MathUtils.normalizeAngle（a，0.0）;

并且看一下源代码，你可以用它来重现它（它们使用自己的 FastMath.floor 但是如果你想在没有外部库的情况下这样做的话）：

And looking at the source code, you could reproduce it with this (they use their own FastMath.floor but in case you want to do it without an external library):

theta - TWO_PI * Math.floor((theta + Math.PI) / TWO_PI)

来源在这里： https://github.com/apache/commons-math/blob/53ec46ba272e23c0c96ada42f26f4e70e96f3115/src/main/java/org/ apache / commons / math4 / util / MathUtils.java＃L107

未来：此方法刚刚（2017年6月）已被删除来自最新的commons-math 4.x代码库。如果您在此之后使用的是某个版本，则需要使用 commons-numbers 相反（一旦发布） - 目前：

Note for readers from the future: this method has just (June 2017) been removed from the latest commons-math 4.x codebase. If you're using a version after this, you'll want to use commons-numbers instead (once it's released) - currently:

a = PlaneAngleRadians.normalizeBetweenMinusPiAndPi(a);

或

a = PlaneAngleRadians.normalize(a, 0.0);

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