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From "Wilhelm Burger (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MATH-1397) Complex.ZERO.pow(2.0) is NaN
Date Thu, 27 Apr 2017 16:27:04 GMT

    [ https://issues.apache.org/jira/browse/MATH-1397?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15986956#comment-15986956
] 

Wilhelm Burger commented on MATH-1397:
--------------------------------------

Thanks - no, I had looked in the wrong place at ["Source code repository (current)" | http://git-wip-us.apache.org/repos/asf/commons-rng.git]
and did not realize the other menu entry further down.

I was able to clone and build the complete repo (with command-line mvn) successfully. However,
importing into Eclipse gave me a couple of errors (apparently related to the maven-antrun-plugin
and checkstyle) which I could not resolve, e.g. (for every pom.xml on line 23):

{noformat}
Plugin execution not covered by lifecycle configuration: org.apache.maven.plugins:maven-antrun-plugin:1.7:run
(execution: javadoc.resources, phase: generate-sources)
pom.xml	/commons-numbers-complex	line 23
{noformat}

Any hints appreciated...

> 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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