using builtin q: I get correct results using
/:~ ~.@, ((*/)@#"1~ #:@:i.@(2&^)@#) 1,q: 4711 1 7 673 4711 /:~ ~.@, ((*/)@#"1~ #:@:i.@(2&^)@#) 1,q: 42 1 2 3 6 7 14 21 42 less brute force but it’s just a first attempt Am 24.04.20 um 20:28 schrieb Skip Cave:
I want to find all the integer factors of a positive integer, which includes 1 and the integer. Here's a brute force verb I wrote: fac=:3 : 'a#~0=(a=.1+i.y)|y' Test it: fac each 40+i.5 │1 2 4 5 8 10 20 40│1 41│1 2 3 6 7 14 21 42│1 43│1 2 4 11 22 44│ However my fac verb is inefficient, slow, and runs out of memory quickly on larger integers. Is there a way to take advantage of J's prime factoring verb q: to more efficiently find and/or count *all* positive factors (not just primes) of a large (>1e7) integers? Skip Skip Cave Cave Consulting LLC ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
-- ---------------------- mail written using NEO neo-layout.org ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
