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https://issues.apache.org/jira/browse/MATH-1185?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14264718#comment-14264718
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Gilles commented on MATH-1185:
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bq. f(130)/100 would be the same number of digits but the exponent would change
to -18.
Yes, but the problem is in computing "f".
Once the value of is "too close" to 1, it's too late: f / 100 would just be
0.01.
IIUC, you propose that some function "g" is computed instead, such that f = g *
100.
bq. Stats packages like R, dcdf, Excel must be compromising with the precision
\[...\]
I guess that they do all the calculations with higher precision and that the
resulting type is not "double".
> Tail probability drops to zero beyond 10e-17 ?
> ----------------------------------------------
>
> Key: MATH-1185
> URL: https://issues.apache.org/jira/browse/MATH-1185
> Project: Commons Math
> Issue Type: Wish
> Affects Versions: 3.3, 3.4
> Reporter: Sriram Natarajan
> Priority: Minor
>
> This could be a simple question, In which case I can expect a clarification.
> If this is the wrong place to post such a question, let me know.
> OS: Windows 8.1, Java 1.8.0_25
> ChiSquaredDistribution chisq = new ChiSquaredDistribution(23)
> 1.0 - chisq.cumulativeProbability(130) is 1.1102230246251565E-16
> 1.0 - chisq.cumulativeProbability(131) is 0.0
> Am pretty sure it is not a formatting issue. Is there a reason why the tail
> drops to zero at this point?
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