function AAin = f2w_aux(m,n)
% A=AAin{i} is a matrix such that 
% max(A*f) = w(i)

mn = m^n;
A = zeros(0,mn);
AAin = repmat({A},[1 n]);
MN = repmat([m],[1 n]);
for ind1 = 1:mn
  for ind2 = ind1+1:mn
    x = ind2coord(ind1,MN);
    y = ind2coord(ind2,MN);
    ii = find(x~=y);
    if length(ii)==1  % Hamming dist == 1
      A = AAin{ii};
      for s = [-1,1]
        rind = size(A,1);
        rind = rind+1;
        A(rind,ind1) =  s;
        A(rind,ind2) = -s;
      end
      AAin{ii} = A;
    end
  end
end
return