function shaped_vals = shape(rec_symbol, Mr, U, N);% shaped_vals = shape(rec_symbol, Mr, U, N);%% This function shapes the received symbols prior to demodulation.  This completes the% decomposition of the channel into parallel subchannels.%%   rec_symbol - received symbol after IFFT block%   Mr - # receive antennas%   U - matrix of unitary matrices premultiplying MIMO subchannels%   N - # OFDM subchannelsshaped_vals =[];for i = 1:N    shaped_vals = [shaped_vals; [U(:,(i-1)*Mr+1:i*Mr)]'*transpose(rec_symbol((i-1)*Mr+1:i*Mr))];endshaped_vals = transpose(shaped_vals);