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Posted to issues@commons.apache.org by "Otmar Ertl (JIRA)" <ji...@apache.org> on 2015/09/09 18:52:45 UTC

[jira] [Commented] (MATH-1269) FastMath.exp may return NaN for non-NaN arguments

    [ https://issues.apache.org/jira/browse/MATH-1269?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14737181#comment-14737181 ] 

Otmar Ertl commented on MATH-1269:
----------------------------------

I have an objection. The patch changes the result of FastMath.exp(709.0001) from 8.219229343394329E307 to Double.POSITIVE_INFINITY. Although this kind of error is less harmful than that caused by the bug, I would prefer a more rigorous solution.

> FastMath.exp may return NaN for non-NaN arguments
> -------------------------------------------------
>
>                 Key: MATH-1269
>                 URL: https://issues.apache.org/jira/browse/MATH-1269
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 4.0
>            Reporter: Otmar Ertl
>         Attachments: MATH-1269.patch
>
>
> I have observed that FastMath.exp(709.8125) returns NaN. However, the exponential function must never return NaN (if the argument is not NaN). The result must always be non-negative or positive infinity.



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