DSP using Matlab 书内练习Example 2.1 - 跑啊跑

先上代码，后出结果图。

a、

n = [-5:5];
x=2*impseq(-2,-5,5) - impseq(4,-5,5);

set(gcf,\'Color\',[1,1,1])                  % 改变坐标外围背景颜色
stem(n,x); title(\'Sequence in Problem 2.1a\');
xlabel(\'n\'); ylabel(\'x(n)\'); grid on;

b、

n = [0:20]; 
x1 = n .* (stepseq(0,0,20) - stepseq(10,0,20));
x2 = 10 * exp(-0.3*(n-10)) .* (stepseq(10,0,20) - stepseq(20,0,20));
x = x1 + x2;

set(gcf,\'Color\',[1,1,1])                  % 改变坐标外围背景颜色
stem(n,x); title(\'Sequence in Problem 2.1b\')
xlabel(\'n\'); ylabel(\'x(n)\');grid on;

　　

 

c、

n = [0:50]; x = cos(0.04*pi*n)+0.2*randn(size(n));

set(gcf,\'Color\',[1,1,1])                  % 改变坐标外围背景颜色
stem(n,x); title(\'Sequence in Problem 2.1c\')
xlabel(\'n\');  ylabel(\'x(n)\'); grid on;

　　

d、

%% 
%% x(n) = {...,5,4,3,2,1,5,4,3,2,1,5,4,3,2,1,...}; -10<n<9
%%                       *

n = [-10:9]; x = [5,4,3,2,1];
xtilde = x\' * ones(1,4); xtilde = (xtilde(:))\';
%subplot(2,2,4);
set(gcf,\'Color\',\'white\');
stem(n,xtilde); title(\'Sequence in Problem 2.1d\')
xlabel(\'n\'); ylabel(\'xtilde(n)\');grid on;