Cosine Similarity in Swift

CosineSimilarity.swift

/** Cosine similarity **/
private func cosineSim(A: [Double], B: [Double]) -> Double {
    return dot(A: A, B: B) / (magnitude(A: A) * magnitude(A: B))
}

/** Dot Product **/
private func dot(A: [Double], B: [Double]) -> Double {
    var x: Double = 0
    for i in 0...A.count-1 {
        x += A[i] * B[i]
    }
    return x
}

/** Vector Magnitude **/
private func magnitude(A: [Double]) -> Double {
    var x: Double = 0
    for elt in A {
        x += elt * elt
    }
    return sqrt(x)
}