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Date: Mon, 1 May 2017 23:07:05 +0000 (UTC)
From: "Gilles (JIRA)" <jira@apache.org>
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Subject: [jira] [Resolved] (MATH-1414) Method reciprocal() in Complex for
 complex numbers with parts very close to 0.0
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archived-at: Mon, 01 May 2017 23:07:09 -0000


     [ https://issues.apache.org/jira/browse/MATH-1414?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gilles resolved MATH-1414.
--------------------------
    Resolution: Won't Do

Issue to be fixed in "Commons Numbers": see NUMBERS-22.

> Method reciprocal() in Complex for complex numbers with parts very close to 0.0
> -------------------------------------------------------------------------------
>
>                 Key: MATH-1414
>                 URL: https://issues.apache.org/jira/browse/MATH-1414
>             Project: Commons Math
>          Issue Type: Improvement
>            Reporter: Gunel Jahangirova
>            Priority: Minor
>             Fix For: 4.0
>
>
> In class Complex method reciprocal() returns INF only if the real and imaginary parts are exactly equal to 0.0. In the cases when real and imaginary parts are double numbers very close to 0.0, it does not hold. For example, if we run this code
> {code}
> Complex complex0 = new Complex((-2.44242319E-315));
> Complex complex1 = complex0.reciprocal();
> {code}
> the value of complex1.getReal() will be -Infinity and the value of complex1.getImaginary() will be NaN, instead of complex1 being equal to INF.
> I think the code in the method 
> {code}
> if (real == 0.0 && imaginary == 0.0) {
>       return INF;
> }
> {code}
> should be replaced by the equality check with some tolerance (0.01 in this case):
> {code}
> if (equals(this, ZERO, 0.01)) {
>      return INF;
> }
> {code}


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