Random.h

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// ---------------------------------------------------------------------
// $Id: Random.h 156 2008-06-08 07:13:49Z daaugusto $
//
//   Random.h (created on Tue Nov 08 01:08:35 BRT 2005)
// 
//   Genetic Algorithm File Fitter (gaffitter)
//
//   Copyright (C) 2005-2008 Douglas A. Augusto
// 
// This file is part of gaffitter.
// 
// gaffitter is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3 of the License, or (at
// your option) any later version.
// 
// gaffitter is distributed in the hope that it will be useful, but
// WITHOUT 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
// along with gaffitter; if not, see <http://www.gnu.org/licenses/>.
//
// ---------------------------------------------------------------------

#ifndef random_hh
#define random_hh

#include <cstdlib>
#include <cmath>
#include <ctime>

// ---------------------------------------------------------------------
class Random {
public:
   static unsigned long Seed(unsigned long seed = 0L) 
   { 
      srand(seed = (seed == 0L) ? time(NULL) : seed);
      return seed;
   }

   static unsigned long Int() { return rand(); }

   static long Int(long a, long b)
   {
      return a + static_cast<long>( Int()*(b-a+1.0) / (RAND_MAX+1.0) );
   }    

   static double Real(double a=0.0, double b=1.0)
   {
      return a + Int()*(b-a) / RAND_MAX;
   }

   /* Non Uniform Random Numbers
    *
    * 'weight = 1': uniform distribution between 'a' and 'b' [a,b]
    * 'weight > 1': non uniform distribution towards 'a'
    * 'weight < 1': non uniform distribution towards 'b'
    */

   static long NonUniformInt(double weight, long a, long b)
   {
      return static_cast<long>(pow(Real(0.0, 1.0), weight) * (b-a) + a);
   }

   static double NonUniformReal(double weight, double a=0.0, double b=1.0)
   {
      return pow(Real(0.0, 1.0), weight) * (b-a) + a;
   }

   static bool Probability(double p)
   {
      if (p <= 0.0) return false;
      if (p >= 1.0) return true;

      return (Real(0.0,1.0) < p) ? true : false;
   }
};

// --------------------------------------------------------------------

#endif