[julia-users] How to calculate all Euclidean distances between two sets of points in a 3-dimensional space

[Carlos Baptista]

Let's say I have two sets of points in a 3-dimensional space represented by 
arrays of sizes Nx3 and Mx3. What is the most efficient way to calculate 
the distances between all points of set 1 against all points of set 2?

This is a (not so efficient example) of what I want to accomplish:


function euclidean_distance(pointA::AbstractMatrix, pointB::AbstractMatrix)
    N = size(pointA, 1)
    M = size(pointB, 1)

    D = zeros(N, M)
    for j = 1:M
        for i = 1:N
            D[i, j] = norm(pointA[i, :] - pointB[j, :])
        end
    end
    
    return D
end