代码:
%% ------------------------------------------------------------------------ %% Output Info about this m-file fprintf(' *********************************************************** '); fprintf(' <DSP using MATLAB> Problem 2.9 '); banner(); %% ------------------------------------------------------------------------ nx = [0:1:20]; x = 0.9 .^ nx; ny = [-20:1:0]; y = 0.8 .^ (-ny); figure('NumberTitle', 'off', 'Name', 'Problem 2.9') 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('n'); ylabel('x(n)') ; grid on subplot(2,1,2); stem(ny, y); title('y sequence'); xlabel('n'); ylabel('y(m)'); grid on; [x1, nx1] = sigfold(x, nx); % obtain x(-n) [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 2.9') 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;
运行结果: