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https://issues.apache.org/jira/browse/MATH-1269?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thomas Neidhart updated MATH-1269:
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Attachment: MATH-1269_fix_z.patch
I propose another patch for this issue.
The polynomial expansion for z = exp(epsilon) - 1.0 is actually returning wrong
results in case epsilon = 0.
The patch handles this case and further fixes the calculation of
(1+z)(tempA+tempB) in case z is 0 as well (in which case we only have to add
tempA and tempB).
This would fix your case as well and other potential cases in the range [0,
709] for which the epsilon is also 0.
> 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, MATH-1269_fix_z.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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