(*exemples introductifs*)

let val_abs (x : float) : float =
    if x >= 0. then x else -. x ;;

let racine (a : float) (b : float) (c : float) : float * float =
    let delta = b*.b -. 4.*.a*.c in
        if delta >= 0. then ((-.b -. sqrt(delta))/.(2.*.a),
                             (-.b +. sqrt(delta))/.(2.*.a))
                       else failwith ("pas de racines") ;;

let rec fact (n : int) : int =
    if (n=0 || n=1) then 1 
                    else n * fact (n-1);;

let affine (a : float) (b : float) : float-> float =
    fun x -> a *. x +. b ;;

let compo (f : int -> int) (g : int -> int) : int-> int =
    fun x -> g (f x) ;;

let racine (a : float) (b : float) (c : float) : float * float =
    let delta = b *. b -. 4. *. a *. c in
        if delta >= 0. then ((-.b -. sqrt(delta))/. (2.*.a),
                             (-.b +. sqrt(delts))/. (2.*.a))
                       else failwith ("pas de racines") ;;

let rec fact (n : int) : int =
    if (n=0 || n=1) then 1 
                    else n * fact (n-1);;

let affine (a : float) (b : float) : float-> float =
    fun x -> a *. x + .b ;;

let compo (f : int -> int) (g : int -> int) : int-> int =
    fun x -> g (f x) ;;

(* exemples de definitions globales *)

let x=1 ;;
let y=x+1;;
y;;
let x=3;;
 y;;
let y=x+1;;
 y;;


(* exemples de definitions locale *)
let a=3 in a+1 ;;
  a;;

let a=3 in let b=a+1;;


(* definitions simultanées : valeur de w ? *)
let x=2;;

let z=3;;

let x=12 and w=x+1 in w;;
      
let x=12 and w=z+1 in w;;

  (* operations sur int, float et char *)

1.5 +. (float_of_int 2);;
int_of_float 3.6 ;;

Char.code 'x' ;;
Char.code y ;;
Char.chr 120 ;;
Char.uppercase 'X' ;;


  (* definition et utilisation de fonctions *)

let carre (x:int) : int = x*x ;;

(carre 5) ;;
    
let moyenne (x:int) (y:int) : int =
    (x+y)/2 ;;







     
let moy_ol (a:int) (b:int) (c:int) (d:int) : float = 
   (float_of_int (a+b+c+d-(min4 a b c d) - (max4 a b c d)))/. 2.0;;




type age = int;; (* age compris entre 0 et 130 *)