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       1             : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
       2             : /*
       3             :  * This file is part of the LibreOffice project.
       4             :  *
       5             :  * This Source Code Form is subject to the terms of the Mozilla Public
       6             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       7             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
       8             :  *
       9             :  * Contributor(s):
      10             :  *   Copyright (C) 2012 Tino Kluge <tino.kluge@hrz.tu-chemnitz.de>
      11             :  *
      12             :  */
      13             : 
      14             : #include <boost/random.hpp>
      15             : 
      16             : // this is nothing but a simple wrapper around
      17             : // the boost random generators
      18             : 
      19             : namespace sc
      20             : {
      21             : namespace rng
      22             : {
      23             : 
      24             : // underlying random number generator
      25             : // boost::mt19937 implements the Mersenne twister algorithm which
      26             : // is fast and has good statistical properties, it produces integers
      27             : // in the range of [0, 2^32-1] internally
      28             : // memory requirement: 625*sizeof(uint32_t)
      29             : // http://en.wikipedia.org/wiki/Mersenne_twister
      30             : #define BOOST_RNG_ALGO  boost::mt19937
      31           5 : BOOST_RNG_ALGO global_rng;
      32             : 
      33             : // initialises the state of the global random number generator
      34             : // should only be called once at the start of the main programme
      35             : // (note, a few boost::variate_generator<> (like normal) have their
      36             : // own state which would need a reset as well to guarantee identical
      37             : // sequence of numbers, e.g. via myrand.distribution().reset())
      38           5 : void seed(int i)
      39             : {
      40           5 :     global_rng.seed(i);
      41           5 : }
      42             : 
      43             : // uniform [0,1) or [a,b) distribution
      44           0 : double uniform()
      45             : {
      46           0 :     static boost::uniform_01<BOOST_RNG_ALGO&> myrand(global_rng);
      47           0 :     return myrand();
      48             : }
      49             : 
      50             : } // namespace
      51          15 : } // namespace
      52             : 
      53             : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */