MATLAB: Manipulation of matrix addition and multiplication.

Question

Hello Friends,

I have the following:

A = [1 2 3; 4  5 6; 7 8 9];
B = [10 11 12; 13 14 15];
[N1, D1] = size(A);
[N2, D2] = size(B);
A_sq = sum(A.^2, 2);
B_sq = sum(B.^2, 2)';
D = A_sq(:,ones(1,N2)) + B_sq(ones(1,N1),:) - 2.*(A*B');

where D is N1 x D1 matrix.

I want to write expression for D in one single step, i.e., something like this (this is for illustration purpose, but it should compute the same Euclidean distance as the code above):

D = sum(X - C).^2;

I will appreciate any advise.

Answer 1

 Bp=permute(B,[3,2,1]);
 D=reshape(   sum(bsxfun(@minus, A, Bp).^2,2))    , N1,N2);