function [C,csig] = qam_constellation(M)% a convenient quantityN = sqrt(M/4);					% M = 4N^2% check if valid M (via checking if N is an integer)if N ~= floor(N),   error('M must be of the form 4*N^2 for integer N'); end% generate constellation pointsC=2*[0:sqrt(M)-1]-sqrt(M)+1;C=ones(sqrt(M),1)*C;C=C+i*C';C=C(:);csig=sqrt(mean(abs(C).^2));C=C/csig;