如何比较该双打序列都是“大致相等”的。在Java？ [英] How to compare that sequence of doubles are all "approximately equal" in Java?

问题描述

我在java中有一个返回双数的方法，我想比较每次调用方法时返回的每个双数（比如说5次），这样我就可以得出结论返回的数字几乎是一样的每一次。

I have a method in java that returns a double number and I want to compare every double number that is returned every time I call the method(say 5 times), so that I can conclude that the number returned is almost the same every time.

我该怎么做？

推荐答案

您必须先确定几乎相同的含义。例如， java.lang.Math 中有一个名为 ulp（），给定一个double，返回该double和next之间的距离;即，该数字与任何其他数字之间的最小可能差异。您可以简单地比较两个双打之间的差异以及调用该方法的结果。

You must first decide what "almost the same" means. For example, there's a method in java.lang.Math called ulp() which, given a double, returns the distance between that double and the next; i.e., the smallest possible difference between that number and any other. You might simply compare the difference between the two doubles and the result of calling that method.

另一方面，也许您希望两个数字仅在1％之内彼此。在这种情况下，执行相同的计算，但使用第一个数字乘以 0.01 而不是 ulp（）作为最大可接受距离。

On the other hand, maybe you want two numbers to just be within 1% of eachother. In that case, do the same computation, but use the first number multiplied by 0.01 instead of ulp() as the largest acceptable distance.

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