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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 */ |