《DSP using MATLAB》Problem 2.5

2、代码：

%% ------------------------------------------------------------------------
%%            Output Info about this m-file
fprintf('
***********************************************************
');
fprintf('        <DSP using MATLAB> Problem 2.5.2 

');

time_stamp = datestr(now, 31);
[wkd1, wkd2] = weekday(today, 'long');
fprintf('      Now is %20s, and it is %7s  

', time_stamp, wkd2);
%% ------------------------------------------------------------------------

n1 = -100; n2 = 100;
n = [n1:n2];
x = exp(0.1* j * pi* n);
%x = cos(0.1 * n);

set(gcf,'Color','white'); 
stem(n,x); title('exp(0.1jpi n) Sequence');
xlabel('n'); ylabel('x(n)'); grid on;

figure
set(gcf,'Color','white'); 
stem(n,real(x)); title('exp(0.1jpi n) Real Part Sequence');
xlabel('n'); ylabel('Real[x(n)]'); grid on;

figure
set(gcf,'Color','white'); 
stem(n,imag(x)); title('exp(0.1jpi n) Imaginary Part Sequence');
xlabel('n'); ylabel('Imag[x(n)]'); grid on;

figure
set(gcf,'Color','white'); 
stem(n,abs(x)); title('exp(0.1jpi n) Magnitude Sequence');
xlabel('n'); ylabel('|x(n)|'); grid on;

figure
set(gcf,'Color','white'); 
stem(n,(180/pi) * angle(x)); title('exp(0.1jpi n) Phase Sequence');
xlabel('n'); ylabel('phase[x(n)]'); grid on;

　　运行结果：

3、代码：

%% ------------------------------------------------------------------------
%%            Output Info about this m-file
fprintf('
***********************************************************
');
fprintf('        <DSP using MATLAB> Problem 2.5.3 

');

time_stamp = datestr(now, 31);
[wkd1, wkd2] = weekday(today, 'long');
fprintf('      Now is %20s, and it is %7s  

', time_stamp, wkd2);
%% ------------------------------------------------------------------------

n1 = -20; n2 = 20;
n = [n1:n2];
%x = exp(0.1* j * pi* n);
x = cos(0.1 * n);

set(gcf,'Color','white'); 
stem(n,x); title('cos(0.1n) Sequence');
xlabel('n'); ylabel('x(n)'); grid on;

　　运行结果：