计算最后一个单位（ULP）双打 [英] Calculate the unit in the last place (ULP) for doubles

问题描述

.NET是否具有内置方法来计算给定双倍的 ULP 或float？

Does .NET have a built-in method to calculate the ULP of a given double or float?

如果没有，最有效的方法是什么？

If not, what is the most efficient way to do so?

推荐答案

似乎函数很简单;这是基于由vulkanino链接的问题的接受答案中的伪代码：

It seems the function is pretty trivial; this is based on the pseudocode in the accepted answer to the question linked by vulkanino:

double value = whatever;
long bits = BitConverter.DoubleToInt64Bits(value);
double nextValue = BitConverter.Int64BitsToDouble(bits + 1);
double result = nextValue - value;

对于浮点数，您需要提供自己的 SingleToInt32Bits 和 Int32BitsToSingle ，因为BitConverter没有这些功能。

For floats, you'd need to provide your own implementation of SingleToInt32Bits and Int32BitsToSingle, since BitConverter doesn't have those functions.

此页面显示了特殊的案例在java实现的功能;处理这些应该也是相当微不足道的。

This page shows the special cases in the java implementation of the function; handling those should be fairly trivial, too.

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