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From "Gilles (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MATH-620) multiplication of infinity
Date Sat, 24 Sep 2011 10:05:26 GMT
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[ https://issues.apache.org/jira/browse/MATH-620?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13113944#comment-13113944
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Gilles commented on MATH-620:
-----------------------------

Hi.

# I don't really understand the necessity of "getSign". Couldn't you use "Math.signum" for
the same
purpose?
# It would better to merge the assertions on the signs within the main test because, having
them separate forces the operation (add, multiply, ...) to be performed 3 times. Really it
is the same test (two results must be equal, sign included).
# I don't understand the statement with "Complex.valueOf".

Did you notice the MATH-667 issue?

> multiplication of infinity
> --------------------------
>
>                 Key: MATH-620
>                 URL: https://issues.apache.org/jira/browse/MATH-620
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 3.0
>            Reporter: Arne PlĂ¶se
>            Priority: Minor
>         Attachments: ComplexOctaveTest.java, arne_tests.zip, arne_tests.zip
>
>
> Take the following testcase
> {code}
> Assert.assertEquals(neginf, inf* neginf, Double.MIN_VALUE);  // <--Passes ordinary
double
> Assert.assertEquals(new Complex(neginf, 0), new Complex(inf, 0).multiply(new Complex(neginf,
0)));// <-- Fail only real parts no imaginary parts
> {code}
> The outcome of multiply is Complex.INF if one part is infinity.
> why not simply compute the multiplication and thats is?

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