[ https://issues.apache.org/jira/browse/MATH-1185?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14264718#comment-14264718 ]
Gilles commented on MATH-1185: ------------------------------ 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? -- This message was sent by Atlassian JIRA (v6.3.4#6332)