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how to vectorize squared function

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Maximilian Dio
Maximilian Dio on 22 Jul 2021
Edited: Bruno Luong on 22 Jul 2021
Hi I have a problem considering calculating a squared function of a grid
so I have 2 vectors X=rand(N,D) and Y=rand(M,D)
I want to generate a function that returs a matrix s.t.
for i = 1:N
for j = 1:M
r2(i,j) = (X(i,:)-Y(j,:))*L*(X(i,:)-Y(j,:))';
end
end
is there a way to vectorize this cleverly?
It needs to run in Simulink (code generation)

Answers (2)

KSSV
KSSV on 22 Jul 2021
r2 = (X-Y).*L.*(X-Y)';

Bruno Luong
Bruno Luong on 22 Jul 2021
Edited: Bruno Luong on 22 Jul 2021
X=rand(3,10);
Y=rand(4,10);
L=rand(10);
N=size(X,1);
M=size(Y,1);
XX=reshape(X,N,1,[]);
YY=reshape(Y,1,M,[]);
YX=reshape(XX-YY,N*M,[]);
r2=reshape(sum(YX.'.*(L*YX')),[N M])
r2 = 3×4
-0.0902 0.5037 1.1533 1.2152 0.2232 0.4179 1.9723 1.8407 0.4105 -0.1182 2.4237 3.2231

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