.NET 数学库函数 Math.Pow() 对负数开奇数次方结果为 NaN,算 Bug 么?

dwen999 _BBCODE_WROTE:

很奇怪,这应该是个很 Basic 的问题。 如果不算,为什么? 算的话,应该存在很多年了,为什么MS 不改? 是因为网上有很多变通方案吗? MS 不好意思侵权?

msdn.microsoft.com/en-...s5e2h.aspx


转贴:

One of the big upgrades included in .NET 4.0 that seems to have been missed by most commentators is the introduction of support for complex numbers.


If you are a scientist then all I can say is - I'm sorry it has taken till version 4.0 to get complex support in .NET. It might not have been a real problem, as it has always been easy enough to add complex support by way of a custom struct, but its the thought that counts. Now we have a standard complex number facility that means you don't have to go DIY.
The new features are contained in System.Numerics but this isn't included automatically in a startup project - yes complex numbers are still a niche topic. To make use of it you have to right click on the References in the Solution Explorer and add System.Numerics. To make using the new features easier also add:
using System.Numerics;

......

www.i-programmer.info/...-in-c.html


msdn.microsoft.com/en-...s5e2h.aspx




bluebit.hubpages.com/h...s-in-Net-C


www.codeproject.com/Ar...ex-Numbers

第二个参数是个浮点数,浮点数有精度问题,很难判断其倒数是奇数还是偶数

这是我的猜测而已

dwen999 _BBCODE_WROTE:

我给的语句是: tmp = Math.Pow(-27.0, 1.0 / 3.0); // returns NaN. 结果与 msdn 文档描述一致。但我的理解是答案应该是 -3.000 浮点才对。

试一下


Complex.Pow ()

dwen999 _BBCODE_WROTE:

很奇怪,这应该是个很 Basic 的问题。 如果不算,为什么? 算的话,应该存在很多年了,为什么MS 不改? 是因为网上有很多变通方案吗? MS 不好意思侵权?

大文,这是实数的pow函数呢,这很正常。

对复数都可以开方,只要用cos, sin, arctan函数就行了,不过这类需求少所以c++ stl的代码没有移植过来。