The issue is the rank of the @. derived verb No additional problem is introduced through the use of a hook here.
Thanks, -- Raul On Thu, May 25, 2023 at 2:05 PM Martin Kreuzer <i...@airkreuzer.com> wrote: > > In addition, I don't understand why > > f=: (1:)`(* [: $: <:) @. * > > shouldn't suffice, compared to > > f=: (1:)`(] * [: $: <:) @. * > > as > > (* [: $: <:) y > > looks to me like a regular hook. > > -M > > > At 2023-05-25 18:33, you wrote: > > >This is odd. > > > >According to https://code.jsoftware.com/wiki/Vocabulary/atdot f should > >have rank 0 (since v is * here). > > > >But, when I redefine f as > > f=: 1:`(] * [: $:&([echo) <:)@.* > > > >I see that when (f 2 3 5 7 11) is executed, f is being treated as some > >other rank. This does not occur for (f 2 3 5 7). > > > >Using $:@<: works around this issue by using $: with the rank of <: > >(the rank problem with @. would still occur, without triggering a rank > >error). > > > >Also, the j implementation tells me that f has infinite rank - despite > >what nuvoc says and despite the behavior for (f 2 3 5 7): > > > > f b.0 > >_ _ _ > > > >-- > >Raul > > > >On Thu, May 25, 2023 at 11:12 AM Martin Kreuzer <i...@airkreuzer.com> > >wrote: > > > > > Dear all - > > > > > Thought I had succeeded in deducing step by > > step the tacit verb for factorial, > > > > > f=: 1:`(] * [: $: <:)@.* > > > > > when I encountered this: > > > > > f=. 1:`(] * [: $: <:)@.* > > > f 2 3 5 7 > > > 2 6 120 5040 > > > f 2 3 5 7 11 > > > |rank error in f, executing monad $: > > > | f 2 3 5 7 11 > > > > > In contrast this seems to work alright: > > > > > g=. 1:`(] * $: @ <:)@.* NB. dictionary entry > > > g 2 3 5 7 > > > 2 6 120 5040 > > > g 2 3 5 7 11 > > > 2 6 120 5040 39916800 > > > > > JVERSION > > > Engine: j9.4.2/j64avx2/windows > > > Build: commercial/2023-04-10T01:19:53/clang-15-0-7/SLEEF=1 > > > Library: 9.4.21 > > > Platform: Win 64 > > > Installer: j9.4 install > > > InstallPath: d:/program files (non-sys)/j9.4 > > > Contact: www.jsoftware.com > > > > > However, my verb > > > > > f=: 1:`(] * [: $: <:)@.* > > > f 2 3 5 7 11 13 > > > 2 6 120 5040 39916800 6227020800 > > > > > works under v8.07 as expected .... > > > > > Could somebody shed some light on this ? > > > > > -M > > > > > ---------------------------------------------------------------------- > > > 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
