I wish to build an array containing specific multi-index. More precisely, in the 2-D case the multi-index are given by
(i, j) where
0 <= i , j <= N+1 such that
i+j <= N+1. The way I do it is make a (N+1)x(N+1) array and cut it in two along its anti-diagonal, namely
βtab = CartesianIndices((N+1, N+1)) βtab = Tuple.( vec(rotl90( UpperTriangular( rotr90(βtab) ) )) ) filter!(x -> sum(x) ≠ 0, βtab)
Does Julia have features that could be used to implement this in a more elegant way ?