In chapter 34 of "50 Shades", I'm questioning the assertion "any combination of r integers from i.n can be put into one-to-one correspondence with the counting integers " because this seems to contradict these tests: ctoi=: 3 : '+/(>:i.#y)!y' NB. combination to integer ctoi&>3 2 1 4;4 3 2 1;1 2 3 4;3 2 1 5 7 4 4 The first three permutations of the same combination map to different numbers but the last two different combos map to the same number. Am I misinterpreting the assertion? Or does the combination need to be sorted? (ctoi@:/:~) &> 3 2 1 4;4 3 2 1;1 2 3 4;3 2 1 NB. OK 4 4 4 3 but (ctoi@:/:~) &> 0 1 2;0 1 2 3 0 0
-- Devon McCormick, CFA Quantitative Consultant ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
