| 1 | /* glprng02.c */ |
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| 2 | |
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| 3 | /*********************************************************************** |
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| 4 | * This code is part of GLPK (GNU Linear Programming Kit). |
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| 5 | * |
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| 6 | * Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, |
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| 7 | * 2009, 2010 Andrew Makhorin, Department for Applied Informatics, |
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| 8 | * Moscow Aviation Institute, Moscow, Russia. All rights reserved. |
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| 9 | * E-mail: <mao@gnu.org>. |
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| 10 | * |
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| 11 | * GLPK is free software: you can redistribute it and/or modify it |
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| 12 | * under the terms of the GNU General Public License as published by |
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| 13 | * the Free Software Foundation, either version 3 of the License, or |
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| 14 | * (at your option) any later version. |
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| 15 | * |
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| 16 | * GLPK is distributed in the hope that it will be useful, but WITHOUT |
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| 17 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
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| 18 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public |
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| 19 | * License for more details. |
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| 20 | * |
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| 21 | * You should have received a copy of the GNU General Public License |
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| 22 | * along with GLPK. If not, see <http://www.gnu.org/licenses/>. |
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| 23 | ***********************************************************************/ |
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| 24 | |
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| 25 | #include "glpenv.h" |
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| 26 | #include "glprng.h" |
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| 27 | #define xfault xerror |
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| 28 | |
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| 29 | /*********************************************************************** |
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| 30 | * NAME |
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| 31 | * |
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| 32 | * rng_unif_01 - obtain pseudo-random number in the range [0, 1] |
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| 33 | * |
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| 34 | * SYNOPSIS |
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| 35 | * |
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| 36 | * #include "glprng.h" |
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| 37 | * double rng_unif_01(RNG *rand); |
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| 38 | * |
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| 39 | * RETURNS |
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| 40 | * |
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| 41 | * The routine rng_unif_01 returns a next pseudo-random number which is |
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| 42 | * uniformly distributed in the range [0, 1]. */ |
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| 43 | |
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| 44 | double rng_unif_01(RNG *rand) |
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| 45 | { double x; |
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| 46 | x = (double)rng_next_rand(rand) / 2147483647.0; |
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| 47 | xassert(0.0 <= x && x <= 1.0); |
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| 48 | return x; |
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| 49 | } |
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| 50 | |
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| 51 | /*********************************************************************** |
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| 52 | * NAME |
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| 53 | * |
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| 54 | * rng_uniform - obtain pseudo-random number in the range [a, b] |
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| 55 | * |
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| 56 | * SYNOPSIS |
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| 57 | * |
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| 58 | * #include "glprng.h" |
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| 59 | * double rng_uniform(RNG *rand, double a, double b); |
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| 60 | * |
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| 61 | * RETURNS |
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| 62 | * |
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| 63 | * The routine rng_uniform returns a next pseudo-random number which is |
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| 64 | * uniformly distributed in the range [a, b]. */ |
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| 65 | |
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| 66 | double rng_uniform(RNG *rand, double a, double b) |
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| 67 | { double x; |
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| 68 | if (a >= b) |
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| 69 | xfault("rng_uniform: a = %g, b = %g; invalid range\n", a, b); |
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| 70 | x = rng_unif_01(rand); |
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| 71 | x = a * (1.0 - x) + b * x; |
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| 72 | xassert(a <= x && x <= b); |
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| 73 | return x; |
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| 74 | } |
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| 75 | |
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| 76 | /* eof */ |
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