I just use @: by default and @ only when I really mean it. One extra character is a very small price to pay for clarity and insurance against potential performance mishaps as far as I am concerned; I even use, more often than not, the letter o (previously defined as o=. @:) instead of @:.
On Fri, Sep 29, 2017 at 10:50 AM, Raul Miller <[email protected]> wrote: > @ and @: have different meanings, in the general case. > > For common specific cases where they do not have different meanings, > it's reasonable for special code to be used to speed up @ > > Specifically: u@v where u's ranks do not exceed v's ranks and where > v's result shape is depends strictly on its argument shape (or where > v's result shape is constant) probably warrants special code.l > > Thanks, > > -- > Raul > > On Fri, Sep 29, 2017 at 9:53 AM, Erling Hellenäs > <[email protected]> wrote: > > Hi all! > > > > From these simple examples it does not seem to be any difference in time > and > > space requirements between the [:+] syntax and the +@:] syntax. Not even > if > > we insert more brackets. > > > > ts'(i.v) ([:+[:+[:+[:+]) i.v=.1000000' > > > > 0.00936323 1.67808e7 > > > > ts'(i.v) (+@:+@:+@:+@:]) i.v=.1000000' > > > > 0.00935086 1.67808e7 > > > > ts'(i.v) (+@:(+@:(+@:(+@:])))) i.v=.1000000' > > > > 0.00925313 1.67811e7 > > > > > > As we can see using @ instead of @: has a heavy penalty in both time and > > space requirements. > > > > > > ts'(i.v) (+@+@+@+@]) i.v=.1000000' > > > > 0.341589 1.69553e8 > > > > > > Cheers, > > > > Erling > > > > > > On 2017-09-29 05:31, Henry Rich wrote: > >> > >> It seems a bit much to ask Raul to track down a recent email thread. > >> > >> No, @: does not create a namespace. Only explicit entities have a > >> namespace. > >> > >> Henry Rich > >> > >> On 9/28/2017 11:19 PM, Erling Hellenäs wrote: > >>> > >>> On 2017-09-29 04:59, Raul Miller wrote: > >>>> > >>>> I do not know of any definition of "namespace" such that @: creates a > >>>> namespace. > >>>> > >>>> Why do you think that @: creates a namespace? > >>>> > >>>> Thanks, > >>>> > >>> As I said there was a discussion about this in a long thread recently. > >>> Maybe you can find it? This is from what I remember of this thread, > it's not > >>> from my own investigations. > >>> > >>> /Erling > >>> > >>> ---------------------------------------------------------------------- > >>> For information about J forums see http://www.jsoftware.com/forums.htm > >> > >> > >> > >> --- > >> This email has been checked for viruses by AVG. > >> http://www.avg.com > >> > >> ---------------------------------------------------------------------- > >> 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
