function shaped_vals = shape(rec_symbol,Mr,U,N);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%   通過用信道左矩陣過濾接收到的矢量
%   在解調之前完成這個過程
%   這個過程完成將信道分解成平行子信道
%
%   rec_symbol  接收經過IFFT的符號
%   Mr          接收天線數
%   U           子信道復用之前的矩陣
%   N           OFDM子載波數
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

shaped_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))];
end

shaped_vals = transpose(shaped_vals);