src/glprng02.c
author Alpar Juttner <alpar@cs.elte.hu>
Sun, 05 Dec 2010 17:35:23 +0100
changeset 2 4c8956a7bdf4
permissions -rw-r--r--
Set up CMAKE build environment
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/* glprng02.c */
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/***********************************************************************
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*  This code is part of GLPK (GNU Linear Programming Kit).
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*
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*  Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
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*  2009, 2010 Andrew Makhorin, Department for Applied Informatics,
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*  Moscow Aviation Institute, Moscow, Russia. All rights reserved.
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*  E-mail: <mao@gnu.org>.
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*
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*  GLPK is free software: you can redistribute it and/or modify it
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*  under the terms of the GNU General Public License as published by
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*  the Free Software Foundation, either version 3 of the License, or
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*  (at your option) any later version.
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*
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*  GLPK is distributed in the hope that it will be useful, but WITHOUT
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*  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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*  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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*  License for more details.
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*
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*  You should have received a copy of the GNU General Public License
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*  along with GLPK. If not, see <http://www.gnu.org/licenses/>.
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***********************************************************************/
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#include "glpenv.h"
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#include "glprng.h"
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#define xfault xerror
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/***********************************************************************
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*  NAME
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*
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*  rng_unif_01 - obtain pseudo-random number in the range [0, 1]
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*
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*  SYNOPSIS
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*
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*  #include "glprng.h"
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*  double rng_unif_01(RNG *rand);
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*
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*  RETURNS
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*
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*  The routine rng_unif_01 returns a next pseudo-random number which is
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*  uniformly distributed in the range [0, 1]. */
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double rng_unif_01(RNG *rand)
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{     double x;
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      x = (double)rng_next_rand(rand) / 2147483647.0;
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      xassert(0.0 <= x && x <= 1.0);
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      return x;
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}
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/***********************************************************************
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*  NAME
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*
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*  rng_uniform - obtain pseudo-random number in the range [a, b]
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*
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*  SYNOPSIS
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*
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*  #include "glprng.h"
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*  double rng_uniform(RNG *rand, double a, double b);
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*
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*  RETURNS
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*
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*  The routine rng_uniform returns a next pseudo-random number which is
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*  uniformly distributed in the range [a, b]. */
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double rng_uniform(RNG *rand, double a, double b)
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{     double x;
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      if (a >= b)
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         xfault("rng_uniform: a = %g, b = %g; invalid range\n", a, b);
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      x = rng_unif_01(rand);
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      x = a * (1.0 - x) + b * x;
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      xassert(a <= x && x <= b);
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      return x;
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}
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/* eof */