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https://issues.apache.org/jira/browse/MATH-1397?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15986527#comment-15986527
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Gilles commented on MATH-1397:
------------------------------
bq. status of this issue
It has been fixed in the new ["Commons Numbers"
project|http://commons.apache.org/proper/commons-numbers] (see NUMBERS-4).
The {{complex}} package will not be part of the next release of Commons Math.
bq. I told my students to use a "proven" library
I totally agree.
bq. first thing they run across is this bug.
I'm very sorry.
It shows that even after many years, there is still room for improving
supposedly mature code.
bq. What should I tell them now?
Please tell them that they are most welcome to test and review the code, to
provide comments and suggestions, and participate in the development by filing
bug reports and fixing bugs.
"Commons Numbers" is being actively worked on right now.
I hope that we are able to produce the first official release in the coming
weeks.
The new (non-official) artefacts for the "complex" functionality can downloaded
from the [snapshot
repository|https://repository.apache.org/content/repositories/snapshots/org/apache/commons/commons-numbers-complex/1.0-SNAPSHOT/].
bq. I do not know of any other environment with a similar behaviour.
You are quite right.
Eric Barnhill is leading the refactoring, with the explicit goal to make the
behaviour conform to the ISO standard.
I'm sure that he'll welcome your help. If not done already, please subscribe to
the "dev" ML in order to discuss the features which you expect from an
implementation of the concept of "complex numbers".
bq. Wouldn't it be simpler to perform exponentiation in polar form
I certainly agree.
I had a, perhaps naive, proposal aimed at ensuring that the most effective
algorithm would be used for a given computation: see
https://issues.apache.org/jira/browse/NUMBERS-10
Please let us know what you think.
> Complex.ZERO.pow(2.0) is NaN
> ----------------------------
>
> Key: MATH-1397
> URL: https://issues.apache.org/jira/browse/MATH-1397
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.6.1
> Environment: Linux, Java1.7/Java1.8
> Reporter: Mario Wenzel
> Assignee: Eric Barnhill
> Priority: Minor
> Fix For: 4.0
>
>
> ```
> package complextest;
> import org.apache.commons.math3.complex.Complex;
> public class T {
> public static void main(String[] args) {
> System.out.println(Complex.ZERO.pow(2.0));
> }
> }
> ```
> This is the code and the readout is `(NaN, NaN)`. This surely isn't right.
> For one, it should actually be zero
> (https://www.wolframalpha.com/input/?i=(0%2B0i)%5E2) and second of all, the
> documentation doesn't state that anything could go wrong from a Complex
> number that has no NaNs and Infs.
> The other definition states that it doesn't work when the base is Zero, but
> it surely should. This strange corner case destroys any naive implementation
> of stuff wrt the mandelbrot set.
> It would be nice to not have to implement this exception myself.
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