function [s,w] = gerchberg(X,w0,numiter)% function [s,w] = gerchberg(X,w0,numiter)%% Try to find a weight vector w such that%   s = w [x(1) x(2) ... x(N)] = w X% has constant modulus % % w0: initial guess for w (or random if unspecified)% numiter: number of iterations (30)[m,N] = size(X);if (nargin <= 1),    w0 = randn(1,m);	% initial guess of the weight vector wendif (nargin <= 2),    numiter = 30;end    Xi = pinv(X);w = w0;for k = 1:numiter,  y = w*X;  s = y./abs(y);  w = s*Xi;end;s = w*X;