%

x1 = [1 2 3 4];
x2 = [4 3 2 1];
conv(x1, x2)

%
%

Xk = [4 2-3j 3+2j -4+6j 8-7j 8+7j -4-6j 3-2j 2+3j];
Xk.'
X4 = circonv(Xk.', Xk.')

%

a = [4 2-3*i 3+i*2 -4+6*i 8-7*i 8+7*i -4-6*i 3-2*i 2+3*i];
a.'
circonv(a.', a.')

%

cconv(Xk,Xk,9)