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
