Re: [Caml-list] arbitrarily large integers

Re: [Caml-list] arbitrarily large integers

[Yann Régis-Gianas]

Le Mardi 3 Décembre 2002 08:40, Scott J. a écrit :
> Hi,

	Hello,

> is it possible to implement in OCamel arbitrary large integers as
> in Dolphin smalltalk e.g. where e.g. factorial 10000 is evaluated
> very fast

	Yes, it's possible : just use the nums library (documented in the
documentation at http://caml.inria.fr/ocaml/htmlman/manual036.html).

	An example :

#load "nums.cma";;

(* directly with Big_int ... *)
open Big_int

let fact n =
  let rec fact_ acu p =
    if p = zero_big_int then
      acu
    else
      fact_ (mult_big_int acu p) (sub_big_int p unit_big_int)
  in
  fact_ unit_big_int n;;

string_of_big_int (fact (big_int_of_int 10000));;

(* more convenient with Num. *)

open Num

let n_ = num_of_int

let big_fact n =
  let rec fact_ acu p =
    if p = n_ 0 then
      acu
    else
      fact_ (acu */ p) (p -/ (n_ 1))
  in
  fact_ (n_ 1) n;;

string_of_num (big_fact (n_ 10000))


--
Yann Regis-Gianas
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[Caml-list] arbitrarily large integers

[Scott J.]

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Hi, is it possible to implement in OCamel arbitrary large integers as in Dolphin smalltalk e.g. where e.g. 
factorial 10000 is evaluatedvery fast.

thanks

Scott

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Re: [Caml-list] arbitrarily large integers

[Jean-Christophe Filliatre]

Scott J. writes:
 > Hi, is it possible to implement in OCamel arbitrary large integers as in Dolphin smalltalk e.g. where e.g. 
 > factorial 10000 is evaluatedvery fast.

The  Num  library  delivered  with ocaml  implements  arbitrary  large
naturals, integers and rationals. 
See http://caml.inria.fr/ocaml/htmlman/manual036.html

There are also

- an interface of the GNU MP library, by David Monniaux, at 
  http://www.di.ens.fr/~monniaux/download/mlgmp-20021123.tar.gz

- The Numerix library by Michel Quercia, at
  http://pauillac.inria.fr/~quercia/

Hope this helps,
-- 
Jean-Christophe 

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Re: [Caml-list] arbitrarily large integers

[Alain.Frisch]

On Tue, 3 Dec 2002, Scott J. wrote:

> Hi, is it possible to implement in OCamel arbitrary large integers as in Dolphin smalltalk e.g. where e.g.
> factorial 10000 is evaluatedvery fast.

Funny that you mention it, my CDuce prototype use OCaml Nums library to
implement integers, and fact 10000 is one of the examples:

http://www.cduce.org/cgi-bin/cduce?example=integers

I have no experience with other large integers libraries for OCaml...

-- Alain
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