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/* rng1.c (pseudo-random number generator) */
/***********************************************************************
* This code is part of GLPK (GNU Linear Programming Kit).
* Copyright (C) 2003 Free Software Foundation, Inc.
* Written by Andrew Makhorin <mao@gnu.org>.
*
* GLPK 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.
*
* GLPK 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 GLPK. If not, see <http://www.gnu.org/licenses/>.
***********************************************************************/
#include "env.h"
#include "rng.h"
/***********************************************************************
* NAME
*
* rng_unif_01 - obtain pseudo-random number in the range [0, 1]
*
* SYNOPSIS
*
* #include "rng.h"
* double rng_unif_01(RNG *rand);
*
* RETURNS
*
* The routine rng_unif_01 returns a next pseudo-random number which is
* uniformly distributed in the range [0, 1]. */
double rng_unif_01(RNG *rand)
{ double x;
x = (double)rng_next_rand(rand) / 2147483647.0;
xassert(0.0 <= x && x <= 1.0);
return x;
}
/***********************************************************************
* NAME
*
* rng_uniform - obtain pseudo-random number in the range [a, b]
*
* SYNOPSIS
*
* #include "rng.h"
* double rng_uniform(RNG *rand, double a, double b);
*
* RETURNS
*
* The routine rng_uniform returns a next pseudo-random number which is
* uniformly distributed in the range [a, b]. */
double rng_uniform(RNG *rand, double a, double b)
{ double x;
xassert(a < b);
x = rng_unif_01(rand);
x = a * (1.0 - x) + b * x;
xassert(a <= x && x <= b);
return x;
}
/* eof */
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