circonvt.m

很多matlab的源代码

function y = circonvt(x1,x2,N)
% N-point circular convlution between x1 and x2 ; (time-domain)
% -----------------------------------------------------------------
% [y] = circonvt(x1,x2,N)
% y = output seqence containing the circular convolution
% x1 = input sequence of length N1 <= N
% x2 = input sequence of length N2 <= N
% N = size of circular buffer
% Method: y(n) = sum (x1(m)*x2(n-m) mod N)
% check for length x1
if length(x1)>N
    error('N must be >= the length of x1')
end
% check for length x2
if length(x2)>N
    error('N must be >= the length of x2')
end
x1=[x1 zeros(1,N-length(x1))];
x2=[x2,zeros(1,N-length(x2))];
m=[0:1:N-1];
x2=x2(mod(-m,N)+1);
H=zeros(N,N);
for n = 1:1:N
    H(n,:) = cirshftt(x2,n-1,N);
end
y=x1*H';
H