%% ------------------------------------------------------------------------

%%            Output Info about this m-file

fprintf('\n***********************************************************\n');

fprintf('        <DSP using MATLAB> Problem 2.10 \n\n');

banner();

%% ------------------------------------------------------------------------

nx = [0:1:199];

 x = cos(0.2*pi*nx) + 0.5*cos(0.6*pi*nx); 

alpha = 0.1; k = 50;

[xk, nxk] = sigshift(x, nx, k);

[y, ny] = sigadd(x, nx, alpha*xk, nxk);

[x1, nx1] = sigfold(x, nx);
[y1, ny1] = sigfold(y, ny);

[Rxy, nxy] = conv_m(x1, nx1, y, ny);

[Rxx, nxx] = conv_m(x1, nx1, x, nx);

figure('NumberTitle', 'off', 'Name', 'Problem 2.10 original sequence')

set(gcf,'Color',[1,1,1])                  % 改变坐标外围背景颜色

subplot(2,1,1); stem(nx, x); title('x sequence');

xlabel('nx'); ylabel('x(n)') ;

grid on

subplot(2,1,2); stem(ny, y); title('y sequence');

xlabel('ny'); ylabel('y(n)');

grid on;

figure('NumberTitle', 'off', 'Name', 'Problem 2.10 correlation sequence')

set(gcf,'Color',[1,1,1])                  % 改变坐标外围背景颜色

subplot(2,1,1); stem(nxy, Rxy); title('Crosscorrelation Rxy(l) sequence');

xlabel('nxy'); ylabel('Rxy(nxy)') ;

grid on

subplot(2,1,2); stem(nxx, Rxx); title('Autocorrelation Rxx(l) sequence');

xlabel('nxx'); ylabel('Rxx(nxx)');

grid on;