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http://issues.apache.org/bugzilla/show_bug.cgi?id=36215 [EMAIL PROTECTED] changed: What |Removed |Added ---------------------------------------------------------------------------- Status|RESOLVED |REOPENED Resolution|FIXED | ------- Additional Comments From [EMAIL PROTECTED] 2005-08-25 00:45 ------- I really hate to post this but I think this bug is somewhat hard to catch: evolution somehow kicks in...... check this out: before I used the new jar I coded a loop to calculate all the probabilities of the upper tail and sum them to get the upper cumPro, just like textbook definition, but of course, slow. I used the new upperCumulativeProbability method to calculate my example, 5000 200 100 50. used my old looping way calculation and a perl script to cross check. I got exactly the same answer: upper cumPro = 4.407167010070517E-45. Great!!! but, as I used it more, ugly bugs showed up: when I calculate 26896 895 55 19, the new jar with the fix gave me 3.40373618E-10, my old looping way and the perl script says 6.2588249E-15 is right, and the probability(19)= 5.8805728E-15, which is a good comfirmation that the second answer is right, because you can imagine something with a tail of even smaller than E-15 won't accumulate to E-10. I have absolutely no idea where this comes from now: the fixed jar can calculate something as small as 4E-45, as we saw in the first example, which indicates accumulation of numeric error is not happening here; without any knowledge of the source code (not that I can't get it, but I won't be able to understand it at all, as a newbie), I have no idea why it would calculate the second case wrong. you guys might think "hey, these are values small enough to be taken as zero, what's the difference?!" I guess mathematicall precision is what we're after here. my looping code can do the job, but it's gonna be tooo slow imagine you do this over and over. Thanks for everyone's patience and effort in solving this. -- Configure bugmail: http://issues.apache.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug, or are watching the assignee. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
