function v = vecreal(V)% function v = vecreal(V)%% kronecker vec operation: makes vector out of V% v = stack of cols of V% This version: modification to make use of symmetry in V[m,N]=size(V);v = zeros(m*N,1);sqrt2 = sqrt(2);k=0;for i = 1:N,for j = 1:N,   k = k+1;   if (i==j)      v(k) = V(i,i);   elseif (i < j),      v(k) = real(V(i,j))*sqrt2;   else      v(k) = imag(V(j,i))*sqrt2;   endendend