I should've mentioned that -.@-:"n also enjoys integrated rank support ("IRS").-Dan PS: A few more details on IRS are available in Roger's paper http://www.jsoftware.com/papers/rank1.htm , and -.@-:"n is explicitly enumerated among IRS-supported verbs in the general index to J's special code (ie Appendix B of the DoJ): http://www.jsoftware.com/help/dictionary/special.htm Please excuse typos; sent from a phone. > On Aug 19, 2014, at 7:34 PM, Dan Bron <[email protected]> wrote: > > > There is also integrated rank support (a specific category special code) for > dyad -:"n , especially when n=1 (ie matching rows of tables has been made > particularly efficient). > > That said, it's probably worth doing a few performance tests on medium-sized > data sets to compare the performance of -:"1 to that of *./ . ~: rather than > making a substitution on the blind and potentially wasting a 24 hour run (or > more) on the larger, production inputs. > > -Dan > > Please excuse typos; sent from a phone. > >> On Aug 19, 2014, at 6:38 PM, Raul Miller <[email protected]> wrote: >> >> I'd want to see some detailed reference on this issue (~.!.0 on non-numeric >> arrays) before I'd want to blow another day or longer trying to reproduce >> the problem with that change. >> >> Alternatively, I'd want to get into the C implementation and find how this >> could happen. That maybe should be done as a theoretical exercise >> (understanding how the algorithm works and how it can fail) than as a >> practical exercise. >> >> Please also keep in mind that I have not eliminated hardware flaws from the >> plausible cause list. Memory corruption (or things equivalent to memory >> corruption, such as an intermittently failing logic component) is an >> all-too-likely possibility. >> >> Thanks, >> >> -- >> Raul >> >> >> >>> On Tue, Aug 19, 2014 at 5:15 PM, Henry Rich <[email protected]> wrote: >>> >>> ~.!.0 as I understand it uses a different algorithm from ~. even on >>> nonnumerics, and might be worth trying. >>> >>> I am sure that ~.!.0 is much faster than ~. of floating-point arrays of >>> rank > 1. I think ~. is OK when the rank is 1. >>> >>> Henry Rich >>> >>> >>>> On 8/19/2014 2:11 PM, Raul Miller wrote: >>>> >>>> Please include the current time in the sequence of timestamps. The code >>>> was >>>> still running at the point in time where I posted my email. >>>> >>>> That said, at this point, my attempt to interrupt succeeded, and I have >>>> found the line of code which was stalled: > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
