It was inadvertent. In the Dictionary, I think there's no pointer to a definition of the general case. /J
----- Original Message ----- From: "Roger Hui" <[email protected]> To: "Programming forum" <[email protected]> Sent: Monday, May 25, 2009 1:53 PM Subject: Re: [Jprogramming] determinant of 16x15 matrix seems to hang J > It just takes a long time. > > Do you really mean to compute the determinant > of a non-square matrix? For a square matrix > the interpreter uses fast (n^3) special code; > for a non-square matrix, it uses the general !n code. > e.g. > > 6!:2 '-/ .* m' [ m=: 8 8 ?...@$ 10 > 9.24699e_5 > 6!:2 '-/ .* m' [ m=: 8 7 ?...@$ 10 > 0.0602373 > > 6!:2 '-/ .* m' [ m=: 9 9 ?...@$ 10 > 5.81079e_5 > 6!:2 '-/ .* m' [ m=: 9 8 ?...@$ 10 > 0.602606 > > 6!:2 '-/ .* m' [ m=: 10 10 ?...@$ 10 > 0.000100013 > 6!:2 '-/ .* m' [ m=: 10 9 ?...@$ 10 > 5.56612 > > 6!:2 '-/ .* m' [ m=: 11 11 ?...@$ 10 > 6.70476e_5 > 6!:2 '-/ .* m' [ m=: 11 10 ?...@$ 10 > 61.0679 > > > > ----- Original Message ----- > From: John Wilson <[email protected]> > Date: Monday, May 25, 2009 10:33 > Subject: [Jprogramming] determinant of 16x15 matrix seems to hang J > To: Programming forum <[email protected]> > >> This appears to hang J. >> >> M =: ? 16 15$10 >> det =: -/ . * >> N =: det 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
