[Gretl-users] Re: tricks for permutation matrices and vectors?

On Tue, Jun 7, 2022 at 9:42 AM Sven Schreiber <svetosch(a)gmx.net&gt; wrote: > Hi, > > I'm wondering how I can easily construct the index vector associated > with a permutation matrix. Here's an example: > > <hansl> > > pvec = {3,1,2} # given index vector > > matrix P = I(nelem(pvec))[pvec,] # associated permutation matrix > > matrix PT = I(nelem(pvec))[,pvec] # transpose of that > > wanted = {2,3,1} # associated with PT, how ?? > > </hansl> wanted = imaxr(PT)' # = imaxc(P)