代码：
x1 = [1,2,2]; x2 = [1,2,3,4]; y = circonvt(x1,x2,4)
n1 = 0:1:length(x1)-1;
n2 = 0:1:length(x2)-1;
ny = 0:1:length(y)-1;
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%% START a
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figure('NumberTitle', 'off', 'Name', 'Exameple5.14 ')
set(gcf,'Color','white');
subplot(3,1,1); stem(n1,x1); title('sequence x1(n)'); axis([0,5,0,5]);
xlabel('n'); ylabel('x1(n)'); grid on;
subplot(3,1,2); stem(n2,x2); title('sequence x2(n)'); axis([0,5,0,5]);
xlabel('n'); ylabel('x2(n)'); grid on;
subplot(3,1,3); stem(ny,y); title('Circularly convolution sequence y(n)'); axis([0,5,0,20]);
xlabel('n'); ylabel('y(n)'); grid on;
%% -----------------------------------------------------------------
%% END a
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运行结果：