Cosine Similarity

SimuDot.fs

let SimuDot (ratings :(float list)list) (a:int)(u:int)=
        let num =  List.zip ratings.[a] ratings.[u]
                       |> List.sumBy (fun item -> fst item * snd item)
        let d1 = ratings.[a] |> List.sumBy (fun item -> item  * item )
        let d2 = ratings.[u] |> List.sumBy (fun item -> item  * item )

        if d1 = 0.0 || d2 = 0.0 then 0.0 else num / (sqrt d1 * sqrt d2)

let ratings = [[4.;0.;5.;5.];[4.;2.;1.;0.];[3.;0.;2.;4.];[4.;4.;0.;0.];[2.;1.;3.;5.]]
SimuDot ratings 0 1