# Vectorization of Loops with Matrix Multiplications

2 views (last 30 days)
Tommaso Belluzzo on 30 Mar 2020
Answered: Matt Shellhammer on 31 Mar 2020
Hi all. I have the following code which is being repeated many times with different time series and this is producing a huge bottleneck on my code:
%% Example Data
t = 252;
h = randn(252,2);
l = round(0.1 * t,0);
%% Loop
for i = 1:(l - 1)
o_tmp = h(1,:).' * h(1+i,:);
for j = 2:(t - i)
o_tmp = o_tmp + h(j,:).' * h(j+i,:);
end
o_tmp = o_tmp / (t - i);
end
I would like ti know if there is a suitable way to improve it, maybe by vectorizing all computations or just some of them. Any suggestion is more than welcome. Thanks in advance for your help!

#### 1 Comment

David Hill on 30 Mar 2020
It would help if you explained what you are trying to do (big picture).

Matt Shellhammer on 31 Mar 2020
%% Example Data
t = 252;
h = randn(252,2);
l = round(0.1 * t,0);
%% Loop
for i = 1:(l - 1)
o_tmp = (h(1:(t-i),:).' * h((1+i):t,:))/(t-i);
end

R2018a

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