Hm, interesting approach, that of Roger's, I still haven't digested it all, but sometimes it would be nice to be able to tackle these problems the same as everybody else in the world...
On 4 August 2014 20:12, Alex Giannakopoulos <[email protected]> wrote: > I used the following memoized code, > > nextcol =: 3 : 0 > > if. 0=2|y do. -: y > > else. >: 3*y > > end. > > ) > > > colchain =: 3 : 0 M. > > if. y=2 do. 1,2 > > else. chain=. colchain nextcol y > > (>:0{chain),x:y>.1{chain > > end. > > ) > > but it took forever to generate the following I aborted it. > colchain"0 (2}.i.1000001) > > I wonder if I did something wrong. > It seems to work if, for instance, you give > colchain"0 (2+i.9999) > Which makes me think the memoization isn't working > Even my slow Scheme interpreter gives the answer in 10 seconds or so, C++ > in less than a second. > > > OTOH, old hands say that J isn't really meant for recursion. I wonder if > this problem should be tackled differently. > > OK, I'm off to read Roger's post that Dan pointed to... > > > > On 4 August 2014 17:30, mvillarino <[email protected]> wrote: > >> 2014-08-04 14:12 GMT+02:00 Dan Bron <[email protected]>: >> > If you're OK with spoilers, have you seen Roger's Collatz Conjecture >> essay >> > on the Wiki? >> > >> > http://jsoftware.com/jwiki/Essays/Collatz%20Conjecture >> > >> >> ? I googled for information on a J spoiler... but no, I haven't found it. >> Thanks a lot !!! >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> > > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
