[Caml-list] generating random variables

[Caml-list] generating random variables

[Henri Dubois-Ferriere]

[apologies if this is posted twice on the newsgroup; i believe the 
recipients of the mail-list did not get it the first time around]


Hello, 

For some simulation studies,  I need to generate exponential,
gaussian, and poisson random variables. Maybe also some more exotic
ones a little later on.

I have looked around, but did not seem to find any available libraries
for generating random variables (except of course for the uniform
variables in Random). Can anyone point me to such a thing, if it
exists?

Thanks, 

Henri

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Re: [Caml-list] generating random variables

[David Chase]

Have you considered

    http://www.taygeta.com/random/gaussian.html

Google found it for me.  I don't know if that is
enough detail for you.

At 07:55 PM 5/9/2002 +0200, Henri Dubois-Ferriere wrote:
>For some simulation studies,  I need to generate exponential,
>gaussian, and poisson random variables. Maybe also some more exotic
>ones a little later on.

David Chase

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Re: [Caml-list] generating random variables

[Olivier Andrieu]

 Henri Dubois-Ferriere [Thursday 9 May 2002] :
 > I have looked around, but did not seem to find any available
 > libraries for generating random variables (except of course for the
 > uniform variables in Random). Can anyone point me to such a thing,
 > if it exists?

You could use GSL, the GNU scientific library
(http://sources.redhat.com/gsl/). It's written in C of course.

I've made some bindings (not for everything, but the RNGs and random
distributions are working). If you're interested, I can send you the
whole stuff.

      Olivier

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Re: [Caml-list] generating random variables

[Shawn Wagner]

On Thu, May 09, 2002 at 07:55:44PM +0200, Henri Dubois-Ferriere wrote:
> [apologies if this is posted twice on the newsgroup; i believe the 
> recipients of the mail-list did not get it the first time around]
> 
> 
> Hello, 
> 
> For some simulation studies,  I need to generate exponential,
> gaussian, and poisson random variables. Maybe also some more exotic
> ones a little later on.
> 
> I have looked around, but did not seem to find any available libraries
> for generating random variables (except of course for the uniform
> variables in Random). Can anyone point me to such a thing, if it
> exists?
> 

My Stew library (Available at http://raevnos.pennmush.org/code/ocaml.html)
includes some random number stuff. There are a few modules for random number
distributions (Functorized so you can use your choice of actual (P)RNG
generators with them; I like the Mersenne Twister, also part of the
library.), and I just added exponential and poisson distributions after
seeing your email. :)

-- 
Shawn Wagner
shawnw@speakeasy.org
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[Caml-list] Using the O'Caml toplevel inside a C program

[Emmanuel Chailloux]

  Hello,

     I try to use the O'Caml toplevel inside a C program but the result 
does not run.

    I wrote the two following programs : g.ml and p.c :

  g.ml
  -------

open Toploop;;
open Callback;;

print_string "apres les open";;
print_newline();;

let exec s =
   let ast = !parse_toplevel_phrase (Lexing.from_string s) in
   ignore(execute_phrase false Format.std_formatter ast);;

let main() =
   print_string "lancement de main (OCAML)";
   print_newline();
  ();;

Callback.register "exec_ocaml" exec;;
Callback.register "main_ocaml" main;;


p.c
----

#include <stdlib.h>
#include <stdio.h>

#include <caml/mlvalues.h>
#include <caml/callback.h>

int main ( int argc, char ** argv ) {
   value v;
   printf("debut de C\n"); fflush(stdout);
   caml_startup(argv);

   printf("init OCAML\n"); fflush(stdout);
   callback(*caml_named_value("main_ocaml"), Val_unit);
   fflush(stdout);

  ...

   v = copy_string("let x = ref 3;;");
   callback(*caml_named_value("exec_ocaml"), v);
   fflush(stdout);
  ...
   return EXIT_SUCCESS;
}


compilation (MacOSX) :
----------------
$ ocamlc -output-obj toplevellib.cma unix.cma g.ml

camlprog.c: In function `caml_startup':
camlprog.c:39186: warning: implicit declaration of function 
`caml_startup_code'

$ cc -I/usr/local/lib/ocaml -L/usr/local/lib/ocaml camlprog.o p.c -lunix 
-lcamlrun

execution (MacOSX, but I obtain the same behaviour with Linux)  :
-------------
  $ ./a.out
debut de C
 >> Fatal error: Toplevel bytecode executable is corrupted
Fatal error: exception Misc.Fatal_error




I suppose that the problem comes from the toploop.ml file in the 
following expression :

---
let _ =
   Sys.interactive := true;
   Symtable.init_toplevel();
   Compile.init_path()
--
but I'am not sure.

  Is there a solution or another way to do that?


Best regards.
Emmanuel Chailloux...

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Re: [Caml-list] Using the O'Caml toplevel inside a C program

[Xavier Leroy]

>      I try to use the O'Caml toplevel inside a C program but the result 
> does not run.

That's a limitation of programs built with -output-obj: the symbol
table information that is normally saved in bytecode executable files
is not available in the C object file generated by -output-obj;
consequently, neither dynamic loading via Dynlink nor the toplevel can
work.

It's not trivial to work around this issue, so I haven't addressed it
yet.

- Xavier Leroy
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