On Sun, Dec 30, 2012 at 1:19 PM, Pedro Giffuni <p...@apache.org> wrote: > Hi Regina; > > > ----- Messaggio originale ----- >> Da: Regina Henschel > >> >> A >> Implementation of FDIST as defined in ODF1.2 >> >> The function FDIST (part 2, 6.18.22) calculates the left tail (integral from >> 0 >> to x). The function LEGACY.FDIST (part 2, 6.18.23) calculates the right tail >> (integral from x to infinity). The current implemention of FDIST in AOO is >> actually “LEGACY.FDIST”. The function FDIST in documents written with OOo2.x >> are >> different from the function FDIST, which has to be implemented. I do not >> speak >> of the UI names, but of the names in the file. >> > > This sounds like FDIST = 1 - LEGACY.FDIST > > It should be easy to "fix" and I think it should be done before 4.x. > > BTW, I am considering doing something drastic there, like replacing all the > probablilty > distributions with with boost implementations. Would there be any good reason > to > avoid such approach? >
What is the advantage of changing? Risk of any change is introducing a bug. From a user's perspective any difference in calculation, even if "correct" is something that may cause them to halt their work until they understand why their complex calculation gives an answer that is 0.1% different than AOO 3.4.1. So we need both accuracy and release-to-release consistency. Me may improve accuracy and in the process yield results that differ from earlier versions, but this needs to be tracked and communicated to users carefully, so they understand what happened to their spreadsheets. I don't think we want "improvements" to be a surprise for the user, especially since at that point bugs and improvements are indistinguishable to casual examination. If we don't have a solid test suite to determine whether our calculations are correct or even detect if our calculations differ from release to release then I'm not really in favor of changing the code. But if we wanted to do a rigorous test of OpenOffice, per the standard, and fix any bugs or inaccuracies that the test suite reveals, then I think we end up with a stronger product, and one where we can safely optimize the routines, knowing that the test cases "have our back". -Rob > Pedro.
