matrixmultip.fsx

#r "/Users/damir/packages/MathNet.Numerics.3.0.2/lib/net40/MathNet.Numerics.dll";;
#r "/Users/damir/packages/MathNet.Numerics.FSharp.3.0.2/lib/net40/MathNet.Numerics.FSharp.dll";;

open MathNet.Numerics.LinearAlgebra

let splitRows (matrix:string) =
    matrix.Split([|'\n'|])
    |> List.ofArray

let parseRow (row:string) =
    row.Split([|' '|])
    |> List.ofArray
    |> List.map (fun x -> float x)

let stringToLists (m:string) =
    m
    |> splitRows
    |> List.map parseRow

let stringToMatrix m =
    m
    |> stringToLists
    |> matrix

let m1s = "2 4\n1 2"
let m2s = "3 2\n4 6"

// one liner:
// "3 4\n1 2".Split([|'\n'|]) |> List.ofArray |> List.map (fun row -> row.Split([|' '|]) |> List.ofArray |> List.map (fun x -> float x)) |> matrix

// one  liner in Ruby (except there's no tranformation to matrix):
// "3 4\n1 2".split("\n").map { |row| row.split(' ').map(&:to_f) }

let m1 = stringToMatrix m1s
let m2 = stringToMatrix m2s

let r = m1 * m2
printfn "Result r1: %A" r

let sumProdPairs = List.fold (fun acc (x, y) -> acc + x * y) 0.
let dotProduct x y = List.zip x y |> sumProdPairs

let rec transpose = function
| (_::_)::_ as M -> List.map List.head M :: transpose ( List.map List.tail M)
| _ -> []

let multip m1 m2 =
  m1
  |> List.map (fun row -> (m2 |> transpose |> List.map (fun col -> dotProduct row col)))

let m1l = stringToLists m1s
let m2l = stringToLists m2s

let r2 = multip m1l m2l
printfn "Result r2: %A" r2