search for: cwilcox

I am a newbie to C (although I did some programming in Perl and Pascal) so forgive me for the language that follows. I am writing because I have a question concerning the *implementation of *(the internal function)* cwilcox* in https://svn.r-project.org/R/!svn/bc/81274/branches/R-DL/src/nmath/wilcox.c. This function is used to determine the test statistics of the Wilcoxon-Mann-Whitney U-test. ______________________________________________________________________________________________________________________________...

...`dwilcox`. Examples are included below. I can?t think of any other ways to improve runtime at this point. That?s not to say there aren?t any, though?I?m hopeful inspection by someone else could identify more ways to save some time. This version uses Andreas?s algorithm for computing the value of `cwilcox`, but evaluates it lazily and caches results. Memory usage of this should be orders of magnitude less than the current version, and recursion is eliminated. As far as I can tell, the numerical accuracy of the results is unchanged. Performance statistics are interesting. If we assume the two popula...

...n, but `qwilcox(0.5, 50, 51)` runs in 5 > milliseconds. The new version runs in roughly 1 millisecond for both. This > is probably because of internal logic that requires many more `free/calloc` > calls if either population is larger than `WILCOX_MAX`, which is set to 50. > Also because cwilcox_sigma has to be evaluated, and this is slightly more demanding since it uses k%d. There is a tradeoff here between memory usage and time of execution. I am not a heavy user of the U test but I think the typical use case does not involve several hundreds of tests in a session so execution time (my...

...in WRE (explaining that too many calls to R_CheckUserInterrupt() can cause a performance bottleneck, especially when the code is running within a GUI), 2. check (and possibly change) the position of R_CheckUserInterrupt() in some base R functions. For example, moving R_CheckUserInterrupt() from cwilcox() to pwilcox() and qwilcox() in src/nmath/wilcox.c may lead to a significant improvement (while still being feasible in terms of response time). Best, Martin -- apl. Prof. Dr. Martin Becker, Akad. Oberrat Lehrstab Statistik Quantitative Methoden Fakult?t f?r Empirische Humanwissenschaften und...

...at too many > calls to R_CheckUserInterrupt() can cause a performance bottleneck, > especially when the code is running within a GUI), > 2. check (and possibly change) the position of R_CheckUserInterrupt() in > some base R functions. For example, moving R_CheckUserInterrupt() from > cwilcox() to pwilcox() and qwilcox() in src/nmath/wilcox.c may lead to a > significant improvement (while still being feasible in terms of response > time). > > Best, > Martin > > > -- > apl. Prof. Dr. Martin Becker, Akad. Oberrat > Lehrstab Statistik > Quantitative Methode...

...kUserInterrupt() can cause a performance bottleneck, >>> especially when the code is running within a GUI), >>> 2. check (and possibly change) the position of R_CheckUserInterrupt() in >>> some base R functions. For example, moving R_CheckUserInterrupt() from >>> cwilcox() to pwilcox() and qwilcox() in src/nmath/wilcox.c may lead to a >>> significant improvement (while still being feasible in terms of response >>> time). >>> >>> Best, >>> Martin >>> >>> >>> -- >>> apl. Prof. Dr. Mar...

...calls to R_CheckUserInterrupt() can cause a performance bottleneck, >> especially when the code is running within a GUI), >> 2. check (and possibly change) the position of R_CheckUserInterrupt() in >> some base R functions. For example, moving R_CheckUserInterrupt() from >> cwilcox() to pwilcox() and qwilcox() in src/nmath/wilcox.c may lead to a >> significant improvement (while still being feasible in terms of response >> time). >> >> Best, >> Martin >> >> >> -- >> apl. Prof. Dr. Martin Becker, Akad. Oberrat >> Lehr...

...can cause a performance bottleneck, >>>> especially when the code is running within a GUI), >>>> 2. check (and possibly change) the position of R_CheckUserInterrupt() in >>>> some base R functions. For example, moving R_CheckUserInterrupt() from >>>> cwilcox() to pwilcox() and qwilcox() in src/nmath/wilcox.c may lead to a >>>> significant improvement (while still being feasible in terms of response >>>> time). >>>> >>>> Best, >>>> Martin >>>> >>>> >>>> -- &g...