[Jprogramming] stalled J processes

[Dan Bron]

I should've mentioned that -. at -:"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 -. at -:"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 <j at bron.us> 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 <rauldmiller at gmail.com> 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 <HenryHRich at nc.rr.com> 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