《DSP using MATLAB》Problem 4.1

        用到的z变换的计算公式：

        代码：

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%%            Output Info about this m-file
fprintf('
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fprintf('        <DSP using MATLAB> Problem 4.1 

');

banner();
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%% ---------------------------------------------
%%          x2(n)=(0.8)^n*u(n-2)
%% ---------------------------------------------


b = [0, 0, 0.64]; a = [1, -0.8];               %  

[delta, n] = impseq(0, 0, 7);

x2_chk = filter(b, a, delta)

x2_ori = (0.8 .^ n) .* stepseq(2, 0, 7)


%% ---------------------------------------------
%%          x3(n)=[0.5^n+(-0.8)^n]u(n)
%% ---------------------------------------------
b = [2, 0.3]; a = [1, 0.3, -0.4];               %  

[delta, n] = impseq(0, 0, 7);

x3_chk = filter(b, a, delta)

x3_ori = (0.5.^n + (-0.8).^ n) .* stepseq(0, 0, 7)



%% ----------------------------------------------------
%%                x5(n)=[(n+1)3^n]u(n)
%% ----------------------------------------------------
b = [1]; a = [1, -6, 9];               %  

[delta, n] = impseq(0, 0, 7);


x5_chk = filter(b, a, delta)

[y, ny] = stepseq(0, 0, 7); 

x5_ori = ( (n+1) .* 3.^n ) .* stepseq(0, 0, 7)

　　运行结果：