Retour en arriere sur l'exponentiation modulaire, pas correcte

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@4532 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

otherlibs/num/big_int.ml

@@ -531,19 +531,6 @@ let base_power_big_int base n bi =
                then zero_big_int
                else create_big_int (bi.sign) res
 
-(* Modular exponentiation *)
-
-let mod_power_big_int a b c =
-  if b.sign < 0 || c.sign < 0 then invalid_arg "modexp_big_int";
-  if c.sign = 0 then raise Division_by_zero;
-  let na =
-    if a.sign < 0 || ge_big_int a c
-    then mod_big_int a c (* normalize a in the range [0...c[ *)
-    else a in
-  let res_nat = mod_power_nat na.abs_value b.abs_value c.abs_value in
-  { sign = if is_zero_nat res_nat 0 (length_nat res_nat) then 0 else 1;
-    abs_value = res_nat }
-
 (* Coercion with float type *)
 
 let float_of_big_int bi = 

otherlibs/num/big_int.mli

@@ -74,15 +74,10 @@ val power_big_int_positive_int: big_int -> int -> big_int
 val power_int_positive_big_int: int -> big_int -> big_int
 val power_big_int_positive_big_int: big_int -> big_int -> big_int
         (** Exponentiation functions.  Return the big integer
-            representing the first argument [a] raised to the power [b]
-            (the second argument).  Depending
-            on the function, [a] and [b] can be either small integers
-            or big integers.  Raise [Invalid_argument] if [b] is negative. *)
-val mod_power_big_int: big_int -> big_int -> big_int -> big_int
-        (** Modular exponentiation.  [modexp_big_int a b c] returns
-            [a] to the [b]-th power, modulo [c].  Raise [Invalid_argument]
-            if [b] or [c] are negative, and [Division_by_zero] if [c]
-            is zero. *)
+           representing the first argument [a] raised to the power [b]
+           (the second argument).  Depending
+           on the function, [a] and [b] can be either small integers
+           or big integers.  Raise [Invalid_argument] if [b] is negative. *)
 
 (** {6 Comparisons and tests} *)
 

otherlibs/num/nat.ml

@@ -234,34 +234,6 @@ let sqrt_nat rad off len =
   loop ()
  end;;
 
-(* Modular exponentiation.  Return a fresh nat equal to (a ^ b) mod c.
-   We assume c > 0 and a < c. *)
-
-let mod_power_nat a b c =
-  let len_c = length_nat c in
-  let res = make_nat len_c in
-  set_digit_nat res 0 1;
-  let prod = create_nat (2 * len_c) in
-  let modmult_res x =
-    (* res <- res * x mod c *)
-    let len_x = length_nat x in
-    set_to_zero_nat prod 0 (2 * len_c);
-    ignore(mult_nat prod 0 (len_c + len_x) res 0 len_c x 0 len_x);
-    div_nat prod 0 (len_c + len_x) c 0 len_c;
-    blit_nat res 0 prod 0 len_c in
-  let digit = make_nat 1
-  and carry = make_nat 1 in
-  (* Iterate over each bit of b, from most significant to least significant *)
-  for i = length_nat b - 1 downto 0 do
-    blit_nat digit 0 b i 1;
-    for i = 1 to length_of_digit do
-      modmult_res res;                  (* res <- res * res *)
-      shift_left_nat digit 0 1 carry 0 1;
-      if is_digit_odd carry 0 then modmult_res a (* res <- res * a *)
-    done
-  done;
-  res
-
 let power_base_max = make_nat 2;;
 
 match length_of_digit with

otherlibs/num/nat.mli

@@ -62,7 +62,6 @@ external lxor_digit_nat: nat -> int -> nat -> int -> unit = "lxor_digit_nat"
 val square_nat : nat -> int -> int -> nat -> int -> int -> int
 val gcd_nat : nat -> int -> int -> nat -> int -> int -> int
 val sqrt_nat : nat -> int -> int -> nat
-val mod_power_nat : nat -> nat -> nat -> nat
 val string_of_nat : nat -> string
 val nat_of_string : string -> nat
 val sys_nat_of_string : int -> string -> int -> int -> nat

otherlibs/num/test/test_big_ints.ml

@@ -466,24 +466,3 @@ test 3 eq_big_int
  (square_big_int (big_int_of_string "-1"), big_int_of_string "1");;
 test 4 eq_big_int
  (square_big_int (big_int_of_string "-7"), big_int_of_string "49");;
-
-testing_function "mod_power_big_int";;
-
-test 1 eq_big_int
-  (mod_power_big_int (big_int_of_int 0) (big_int_of_int 0) (big_int_of_int 42),
-   big_int_of_int 1);;
-test 2 eq_big_int
-  (mod_power_big_int (big_int_of_int 0) (big_int_of_int 1) (big_int_of_int 42),
-   big_int_of_int 0);;
-test 3 eq_big_int
-  (mod_power_big_int (big_int_of_int 12345) (big_int_of_int 6789)
-                     (big_int_of_string "4782546123567"),
-   big_int_of_string "3726846414024");;
-test 4 eq_big_int
-  (mod_power_big_int (big_int_of_int (-12345)) (big_int_of_int 6789)
-                  (big_int_of_string "4782546123567"),
-   big_int_of_string "1055699709543");;
-test 5 eq_big_int
-  (mod_power_big_int (big_int_of_string "200866937202159") (big_int_of_int 6789)
-                     (big_int_of_string "4782546123567"),
-   big_int_of_string "3726846414024");;