Difference between the individual rows of B and all the rows of A.

Hi everyone.

I have 2 arrays, A (378812x3 double) and B (400x3 double).

I have to calculate the difference between the individual rows of B and all the rows of A.

I tried to use the following formula but it does not run.

How can i do it? Thanks

N=400

for k=1:N

DIF=sqrt((A(:,1)-B(1:N,1)).^2+(TA(:,2)-B(1:N,2)).^2+(A(:,3)-B(1:N,3)).^2);

end

Answer 1

[Bruno Luong]

DIF = zeros(size(A,1),size(B,1))
for k=1:size(B,1)
    DIF(:,k)=sqrt((A(:,1)-B(k,1)).^2+(A(:,2)-B(k,2)).^2+(A(:,3)-B(k,3)).^2);
end

Or simply (if you have the right toolbox)

DIF = pdist2(A,B)

[Guillaume]

You don't even need the toolbox, it's trivial to implement:

DIF = sqrt(sum((permute(A, [1 3 2]) - permute(B, [3 1 2])).^2, 3))

note that permute is an expensive operation so the loop may be faster.