File : a-nuflra.ads
------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
5 -- A D A . N U M E R I C S . F L O A T _ R A N D O M --
-- --
-- S p e c --
-- --
-- $Revision: 1.12 $ --
10 -- --
-- Copyright (C) 1992-1998 Free Software Foundation, Inc. --
-- --
-- This specification is derived from the Ada Reference Manual for use with --
-- GNAT. The copyright notice above, and the license provisions that follow --
15 -- apply solely to the contents of the part following the private keyword. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 2, or (at your option) any later ver- --
20 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
25 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
30 -- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
35 -- GNAT was originally developed by the GNAT team at New York University. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
40 -- Note: the implementation used in this package was contributed by
-- Robert Eachus. It is based on the work of L. Blum, M. Blum, and
-- M. Shub, SIAM Journal of Computing, Vol 15. No 2, May 1986. The
-- particular choices for P and Q chosen here guarantee a period of
-- 562,085,314,430,582 (about 2**49), and the generated sequence has
45 -- excellent randomness properties. For further details, see the
-- paper "Fast Generation of Trustworthy Random Numbers", by Robert
-- Eachus, which describes both the algorithm and the efficient
-- implementation approach used here. This paper is available at
-- the Ada Core Technologies web site (http://www.gnat.com).
50
with Interfaces;
package Ada.Numerics.Float_Random is
55 -- Basic facilities
type Generator is limited private;
subtype Uniformly_Distributed is Float range 0.0 .. 1.0;
60
function Random (Gen : Generator) return Uniformly_Distributed;
procedure Reset (Gen : Generator);
procedure Reset (Gen : Generator; Initiator : Integer);
65
-- Advanced facilities
type State is private;
70 procedure Save (Gen : Generator; To_State : out State);
procedure Reset (Gen : Generator; From_State : State);
Max_Image_Width : constant := 80;
75 function Image (Of_State : State) return String;
function Value (Coded_State : String) return State;
private
type Int is new Interfaces.Integer_32;
80 type Flt is digits 14;
K1 : constant := 94_833_359;
K1F : constant := 94_833_359.0;
K2 : constant := 47_416_679;
85 K2F : constant := 47_416_679.0;
Scal : constant := 1.0 / (K1F * K2F);
type State is record
X1 : Int := 2999 ** 2; -- Square mod p
90 X2 : Int := 1439 ** 2; -- Square mod q
P : Int := K1;
Q : Int := K2;
X : Int := 1;
Scl : Flt := Scal;
95 end record;
type Generator is limited record
Gen_State : State;
end record;
100
end Ada.Numerics.Float_Random;