vectorize a block matrix calculation

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Luis Isaac
Luis Isaac 2017-4-28
编辑： Matt J 2017-4-28
Dear;
I want calculate a big matrix composed of blocks, for that I use the following code:
k=length(a); % Long vector
n=size(xx,1); % 2D or 3D matrix always the same
TP=repmat(zeros(size(xx),k,1); % Big matriz composed by blocks
for i=1:k
TP((i-1)*n+1:i*n,:)=a(i)*xx; % Block i of TP matrix
end
Is there any way to vectorize this code and speed up the calculation Many thanks;

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Matt J
Matt J 2017-4-28
TP=kron(a(:),xx);
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Andrei Bobrov
Andrei Bobrov 2017-4-28
TP = reshape(bsxfun(@plus,xx',reshape(a,1,1,[])),size(x,2),[])'
Matt J
Matt J 2017-4-28
编辑：Matt J 2017-4-28
You could also use my attached tensorfun() utility.
TP=tensorfun(@plus,a(:),xx);
It allows you to do similar things for any block structure and any bi-operand operation (@plus, @minus, etc...) supported by bsxfun.

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