Re: [Gretl-users] Function to get the powerset

On Thu, 11 Oct 2018, Riccardo (Jack) Lucchetti wrote: > If I'm not mistaken, this is more or less what we came up with in the end [...] Actually, this is slightly faster: <hansl> function strings powerset(strings S)     scalar l = nelem(S)     scalar N = 2^l     matrix P = zeros(N,l)     matrix s = seq(0, N-1)'     loop i=1..l --quiet         matrix a = s % 2         matrix P[,i] = a         matrix s = (s-a)/2     endloop     strings PS = array(N)     loop i = 1..N --quiet         string c = ""         loop j = 1..l --quiet             if P[i, j]                 c = c ~ " " ~ S[j]             endif         endloop         PS[i] = c     endloop     return PS end function </hansl>