行移位矢量值

Question

我怎麼能轉移的載體c的條目是這樣的：

c = [1; 2; 0]; 
x = [1; 2; 3]; 

y(1:3) = rightshift(c', 0:2) * x; 

% Should produce: 
% y(1) = [1; 2; 0]' * x; 
% y(2) = [0; 1; 2]' * x; 
% y(3) = [0; 0; 1]' * x; 

產生輸出向量y？

Answer 1

隨着toeplitz -

N = numel(c); 
y = triu(toeplitz(c,0:N-1).')*x 

或用mod & bsxfun -

N = numel(c) 
y = triu(c((mod(bsxfun(@minus,[0:N-1]',0:N-1),N)+1).'))*x 

或者只bsxfun -

N = numel(c); 
c_ext = [zeros(N-1,1) ; c(:)] 
y = c_ext(bsxfun(@plus,[N:-1:1]',[0:N-1]))*x 

Answer 2

這是本質的卷積：

y = conv(c(end:-1:1), x); 
y = y(end-numel(c)+1:end);