Is there an explicit map between Anagram index and inverse Anagram index: Ai: (index,#) -> index
so that it does not expand the index into vector to calculate (purely scalar). Model: Ai=: A.@/:@(A. i.)~"0 4 Ai i.!4 0 1 2 4 3 5 6 7 12 18 13 19 8 10 14 20 16 22 9 11 15 21 17 23 Using it, ([EMAIL PROTECTED] A.~ # Ai A.) p 0 20 3 7 6 19 11 12 8 10 1 15 2 5 21 14 9 4 13 18 16 17 22 --- Roger Hui <[EMAIL PROTECTED]> wrote: > p=: ?~23 > /:p > 0 20 3 7 6 19 11 12 8 10 1 15 2 5 21 14 9 4 13 18 16 17 22 > |.&.>&.C. p > 0 20 3 7 6 19 11 12 8 10 1 15 2 5 21 14 9 4 13 18 16 17 22 > > > > ----- Original Message ----- > From: Roger Hui <[EMAIL PROTECTED]> > Date: Sunday, September 9, 2007 9:06 > Subject: Re: [Jprogramming] inverse permutation vector > To: Programming forum <[email protected]> > > > There is an isomorphism between integer permutation vectors > > and boolean permutation matrices under {= and i."1&1 . > > Therefore: > > > > (/:p) -: |:&.(({=) :. (i."1&1)) p > > > > http://www.jsoftware.com/jwiki/Essays/Symmetries_of_the_Square > > > > > > > > ----- Original Message ----- > > From: Oleg Kobchenko <[EMAIL PROTECTED]> > > Date: Sunday, September 9, 2007 0:16 > > Subject: Re: [Jprogramming] inverse permutation vector > > To: Programming forum <[email protected]> > > > > > Also > > > > > > (i. [EMAIL PROTECTED]) p > > > 0 20 3 7 6 19 11 12 8 10 1 15 2 5 21 14 9 4 13 18 16 17 22 > > > > > > Variation > > > > > > [EMAIL PROTECTED]@]`]`]}~ p > > > 0 20 3 7 6 19 11 12 8 10 1 15 2 5 21 14 9 4 13 18 16 17 22 > > > > > > > > > --- Roger Hui <[EMAIL PROTECTED]> wrote: > > > > > > > Another solution. Both are well-known in APL circles. > > > > > > > > ] p=: ?~23 > > > > 0 10 12 2 17 13 4 3 8 16 9 6 7 18 15 11 20 21 19 5 1 14 22 > > > > /: p > > > > 0 20 3 7 6 19 11 12 8 10 1 15 2 5 21 14 9 4 13 18 16 17 22 > > > > p}~i.#p > > > > 0 20 3 7 6 19 11 12 8 10 1 15 2 5 21 14 9 4 13 18 16 17 22 > > > > > > > > > > > > > > > > ----- Original Message ----- > > > > From: bill lam <[EMAIL PROTECTED]> > > > > Date: Saturday, September 8, 2007 20:01 > > > > Subject: Re: [Jprogramming] inverse permutation vector > > > > To: Programming forum <[email protected]> > > > > > > > > > Raul Miller wrote: > > > > > > ipv=: /: pv > > > > > > > > > > Thank you, I didn't realize that is so simple. > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ____________________________________________________________________________________ Be a better Heartthrob. Get better relationship answers from someone who knows. Yahoo! Answers - Check it out. http://answers.yahoo.com/dir/?link=list&sid=396545433 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
