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给出一个x(t)和h(t)的值：

>> x=[1 -2 3 -4]

x =

     1    -2     3    -4

>> h=[2 2 1 3]

h =

     2     2     1     3

卷积：

>> y=conv(x,h)

y =

     2    -2     3    -1   -11     5   -12

圆周卷积：
通过help cconv我们可以看到圆周卷积相关

 help cconv
 cconv Modulo-N circular convolution.
    C = cconv(A, B, N) circularly convolves vectors A and B.  The resulting
    vector is length N. If omitted, N defaults to LENGTH(A)+LENGTH(B)-1.
    When N = LENGTH(A)+LENGTH(B)-1, the circular convolution is equivalent
    to the linear convolution computed by CONV.
    
    % Example #1: Mod-4 circular convolution
    a = [2 1 2 1];
    b = [1 2 3 4];
    c = cconv(a,b,4)  
 
    % Example #2: Circular convolution as a fast linear convolution
    a = [1 2 -1 1];
    b = [1 1 2 1 2 2 1 1];
    c = cconv(a,b,11)  
    cref = conv(a,b)
 
    % Example #3: Circular cross-correlation
    a = [1 2 2 1]+1i;
    b = [1 3 4 1]-2*1i;
    c = cconv(a,conj(fliplr(b)),7)
    cref = xcorr(a,b)

举例：

y=cconv(x,h,4)

y =

    -9     3    -9    -1