《DSP using MATLAB》Problem5.23

 

代码：

%% ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%%            Output Info about this m-file
fprintf('\n***********************************************************\n');
fprintf('        <DSP using MATLAB> Problem 5.23 \n\n');

banner();
%% ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

% -------------------------------------------------------------------
%               
%                                
% -------------------------------------------------------------------
n = [0:6];
x = [1, 2, -3, 4, -5, 0, 0];
 
N = 7;
x_cir_fold = x(mod(-n, N)+1);

m = -1;

y = cirshftt(x_cir_fold, m, 7);
ny = [0:6];


figure('NumberTitle', 'off', 'Name', 'P5.23 x(n) x((-n)) x((-8-n))')
set(gcf,'Color','white'); 
subplot(3,1,1); stem(n, x); 
xlabel('n'); ylabel('x');
title('x(n), N=7');  grid on;
subplot(3,1,2); stem(n, x_cir_fold);  
xlabel('n'); ylabel('');
title('x((-n)), N=7');  grid on;
subplot(3,1,3); stem(ny, y); 
xlabel('n'); ylabel('y');
title('x((-8-n)), N=7');  grid on;

　　运行结果：