map ((#L:0"1{:),.&;~+/"1@[ #L:0 {.@]) 'abc';'ABCD'
aA
aD
bB
bCMy 2 cts. R.E. Boss -----Original Message----- From: Programming <[email protected]> On Behalf Of bill lam Sent: dinsdag 21 september 2021 11:38 To: Programming forum <[email protected]> Subject: [Jprogramming] cross product Say I have a boolean matrix ] map=. 3 4 $ 1 0 0 1 0 1 1 0 0 0 0 0 1 0 0 1 0 1 1 0 0 0 0 0 and 2 vectors of dimension equal to the 2 sides of the matrix m=. 'abc' [ n=. 'ABCD' I want a cross product for those 1 in the matrix, with result like this _2 ]\ 'aAaDbBbC' aA aD bB bC Is it possible to do it without explicit loops? The dimension of the matrix can be very large so that generating all cross products then eliminating is not an option. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
