Hi, Butch, Several tests to determine whether a number is prime are detailed in the J wiki, here:
http://www.jsoftware.com/jwiki/Essays/Primality%20Tests The Wikipedia article on Wilson's theorem says: "Wilson's theorem is useless as a primality test in practice, since computing (n - 1)! modulo n for large n is hard, and far easier primality tests are known" That recognized, we can of course code that test in J. Hope it doesn't deflate any of your efforts to do so for me to post my solutions here. wilsonX=: verb :'=/ y | _1 , ! y-1x'"_1 wilson0=: (] | _1:) = ] | 1x !...@-~] }.I. wilsonX i. 55 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 }.I. wilson0 i. 55 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 NB. compare: I. 1 p: i.55 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 It's important to note that p: is a primary verb within J. Beyond that, the tests on the previously mentioned wiki page may the most applicable to your quest. Tracy ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
