Vectorization of a nestled loop

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AM
AM 2018-10-12
评论： AM 2018-10-12
I am trying to improve the overall performance of my code and I am learning about vectorization. I've read the documentation on this but I'm having a hard time with even seemingly simple parts of the code. I have the following loop
dndt=zeros(m,1);
for i=1:n
for j=1:m
dndt(j,1)=dndt(j,1)+matA(i,j)*B(i);
end
end
Where matA is a n x m matrix and B is a vector of size n. I'm not sure how to do this.
Any tips or help is appreciated, thank you!

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Stephen23
Stephen23 2018-10-12
编辑：Stephen23 2018-10-12
You can use matrix multiplication:
matA.'*B(:)
which gives an output with size mx1, just like your nested loops. Even simpler:
B*matA
which gives an output with size 1xm.

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