That's because of special code http://www.jsoftware.com/help/release/amipcommute.htm and how it interacts with the ref count. (You do not want to be doing an in-place modification of an array which has multiple references to it.)
Thanks, -- Raul On Wed, Apr 26, 2017 at 10:08 AM, Xiao-Yong Jin <[email protected]> wrote: > f=:4 :'y 0}x' > a=:1e6?@#0 > timespacex'a=:a f 0' > 0.004784 8.39053e6 > timespacex'a=:a 0}~0' > 8e_6 1920 > >> On Apr 25, 2017, at 10:35 PM, Raul Miller <[email protected]> wrote: >> >> What do you mean by "extra copies" and how have you been measuring that? >> >> (Most of the time, a "copy" just means incrementing a reference count. >> There have been some exceptions, though, for boxed data, for example.) >> >> Thanks, >> >> -- >> Raul >> >> >> On Tue, Apr 25, 2017 at 9:19 PM, Xiao-Yong Jin <[email protected]> wrote: >>> >>>> On Apr 25, 2017, at 6:30 PM, Eric Iverson <[email protected]> wrote: >>>> >>>> I have not followed this discussion at all and am probably way off base. >>>> >>>> But how is: >>>> >>>> allocate a few structures, and pass their pointers to the same function in >>>> separate callings >>>> >>>> different from: >>>> >>>> allocated a few globals in an agreed upon locale (call it the heap), and >>>> pass their names (pointers) to the same verb in separate callings >>>> >>>> ? >>> >>> This question is actually right on spot, and I am struggling with this. >>> There are two aspects of this problem in my opinion. >>> >>> 1. Unnecessary copying of data, given the current state of the in-place >>> operations in J. To have a varied state in J, passing names to verb >>> essentially amounts to the following operations, >>> >>> State =. State Verb Control NB. akin to usual functional style >>> >>> Most of the time J would make unnecessary copies of the data in State. >>> I haven't found a reliable way to avoid extra copying, except for when >>> the 'Verb' here is a primitive. >>> >>> 2. Inconvenience, if you want to maintain a set of inhomogeneous states. >>> I can do >>> >>> 'State1A State1B State1C' = (State1A;State1B;State1C) Verb Control >>> 'State2A State2B State2C' = (State2A;State2B;State2C) Verb Control >>> >>> Apart from copying/boxing, there are too many names to keep track of. >>> I would rather do >>> >>> Verb_1_ Control >>> Verb_2_ Control >>> >>> I guess I'm just more familiar with the latter, because it resembles >>> a common C function: >>> >>> void Verb(*Locale, const *Control) >>> >>> Maybe I'm missing something in J. Please feel free to correct me. >>> >>> ---------------------------------------------------------------------- >>> For information about J forums see http://www.jsoftware.com/forums.htm >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
