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https://issues.apache.org/jira/browse/MATH-1414?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15974508#comment-15974508
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Gunel Jahangirova edited comment on MATH-1414 at 4/19/17 12:00 PM:
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In case of Complex(0.0, 0.0) the value calculated for reciprocal is (Infinity,
NaN) and the current implementation returns Inf. Similarly, we could return
{code}Double.NEGATIVE_INFINITY{code}, if the real part of the result is
{code}Double.NEGATIVE_INFINITY{code} and {code}Double.POSITIVE_INFINITY{code}
in case it is {code}Double.POSITIVE_INFINITY{code}.
was (Author: gjahanagirova):
In case of Complex(0.0, 0.0) the value calculated for reciprocal is (Infinity,
NaN) and the current implementation returns Inf. Similarly, we could return
Double.NEGATIVE_INFINITY, if the real part of the result is
Double.NEGATIVE_INFINITY and Double.POSITIVE_INFINITY in case it is
Double.POSITIVE_INFINITY.
> 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
>
> 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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