PDS_kNN/matlab/distXY.m~

function D = distXY(X, Y)
%distXY Calculate an m x n Euclidean distance matrix 𝐷 of X and Y
%
% Calculate an m x n Euclidean distance matrix 𝐷     between two sets points 𝑋 and 𝑌 of 𝑚 and 𝑛 points respectively
% X : [m x d]   Corpus data points (d dimensions)
% Y : [n x d]   Query data poinsts (d dimensions)
% D : [m x n]   Distance matrix where D(i,j) the distance of X(i) and Y(j)

    [m d1] = size(X);
    [n d2] = size(Y);
    if d1 == d2
        d = d1;
    else
        error('Corpus(X) and Query(Y) data points have to have the same dimensions');
    end
    %D = (X.*X) * ones(d,1)*ones(1,n) -2 * X*Y.' + ones(m,1)*ones(1,d) * (Y.*Y).';
    D = sum(X.^2, 2) - 2 * X*Y.' + sum(Y.^2, 2).'
end