Am 11.10.2018 um 23:28 schrieb Riccardo (Jack) Lucchetti: > 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>
Hi Jack, without having checked whether this is intended but the first entry in the PwrSet string array is empty. Artur
