(* calculs sur les polynomes *)let reduit_poly p =  let rec aux = function   | [] -> []   | 0::q -> aux q   | q -> q  in rev(aux(rev p)) ;;let add_poly p q =  let rec add = function   | (a::p,b::q) -> (a+b)::(add(p,q))   | (p,[]) -> p   | ([],q) -> q  in reduit_poly(add(p,q)) ;;let scale_poly k p =  reduit_poly(map (prefix * k) p) ;;let decale_poly k p =  let rec aux q = function   | 0 -> q   | s -> aux (0::q) (s-1)  in reduit_poly(aux p k) ;;let mul_poly p q =  let rec mul = function   | ([],_) | (_,[]) -> []   | (p,t::q) -> let r = scale_poly t p and s = mul(decale_poly 1 p,q)    in add_poly r s  in mul(p,q) ;;let print_poly p =  let tete = function   | (0,t) -> print_int t   | (1,1) -> print_string "X"   | (1,-1) -> print_string "-X"   | (1,t) -> print_int t ; print_string "X"   | (k,1) -> print_string "X^" ; print_int k   | (k,-1) -> print_string "-X^" ; print_int k   | (k,t) -> print_int t ; print_string "X^" ; print_int k  in let autre = function   | (k,t) when t<0 -> tete(k,t)   | (k,t) -> print_string "+" ; tete(k,t)  in let rec deb k = function   | [] -> print_string "0"   | 0::q -> deb (k+1) q   | t::q -> tete(k,t); suite (k+1) q  and suite k = function   | [] -> ()   | 0::q -> suite (k+1) q   | t::q -> autre(k,t); suite (k+1) q  in deb 0 p ;;