type t = float array

let zero =
  [| 0. ; 0. ; 0. |]

let of_float_triplet (x,y,z) =
  [|x;y;z|]

let of_3_floats x y z =
  [|x;y;z|]

let to_string x =
  (string_of_float x.(0))^" "^(string_of_float x.(1))^" "^(string_of_float x.(2))

let x a = a.(0)
let y a = a.(1)
let z a = a.(2)

let coord a = function
| 0 -> a.(0)
| 1 -> a.(1)
| 2 -> a.(2)
| _ -> raise (Invalid_argument "Coordinate")


let to_float_array a = a

(** Linear algebra *)
let (|-) a b =
  match a,b with
  | [|x;y;z|], [|x';y';z'|] -> [| x-.x'; y-.y'; z-.z' |]
  | _ -> assert false


let (|+) a b =
  match a,b with
  | [|x;y;z|], [|x';y';z'|] -> [| x+.x'; y+.y'; z+.z' |]
  | _ -> assert false


let (|.) s a =
  match a with
  | [|x;y;z|] -> [| s*.x; s*.y; s*.z |]
  | _ -> assert false


let dot a b =
  match a,b with
  | [|x;y;z|], [|x';y';z'|] ->  x*.x' +. y*.y' +. z*.z' 
  | _ -> assert false


let norm u =
  sqrt @@ dot u u