euclidean_distance.m

best routing protocol

%calculate the euclidean distance based on coordinate y
%X: Nxd coordinates
%Y: Mxd coordinates
%edist: N x M matrix: edist(i,j) = euclidean_distance(x_i, y_j)
function edist = euclidean_distance(X,Y)
    [N,d] = size(X);
    [M,d1] = size(Y);
    
    xy = X*Y'.*2;
    xx = repmat(sum(X.^2,2), 1, M);
    xx = xx-xy;
    clear  xy;
    t = sum(Y.^2, 2);
    yy = repmat(t', N, 1);
    clear t;
    xx = xx+yy;
    clear yy;
    edist = sqrt(xx);
    return
    
    for i = 1:N
        for j = 1:M
            t = sum((X(i,:)-Y(j,:)).^2);
            if t>0
                edist(i,j) = t^0.5;
            else
                edist(i,j)=0;
            end
        end
    end