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From "Sebb (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MATH-1269) FastMath.exp may return NaN for non-NaN arguments
Date Thu, 10 Sep 2015 19:12:45 GMT

    [ https://issues.apache.org/jira/browse/MATH-1269?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14739394#comment-14739394
] 

Sebb commented on MATH-1269:
----------------------------

Note: I had a quick look at expm1() and that seems to naturally return infinity when required
without needing to check that the input is too large. Unfortunately defining exp() in terms
of expm1() does not retain sufficient precision.

> 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, 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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