forked from github/server
73 lines
1.6 KiB
C
73 lines
1.6 KiB
C
/* vi: set ts=2:
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*
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*
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* Eressea PB(E)M host Copyright (C) 1998-2003
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* Christian Schlittchen (corwin@amber.kn-bremen.de)
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* Katja Zedel (katze@felidae.kn-bremen.de)
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* Henning Peters (faroul@beyond.kn-bremen.de)
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* Enno Rehling (enno@eressea-pbem.de)
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* Ingo Wilken (Ingo.Wilken@informatik.uni-oldenburg.de)
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*
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* based on:
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*
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* Atlantis v1.0 13 September 1993 Copyright 1993 by Russell Wallace
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* Atlantis v1.7 Copyright 1996 by Alex Schröder
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*
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* This program may not be used, modified or distributed without
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* prior permission by the authors of Eressea.
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* This program may not be sold or used commercially without prior written
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* permission from the authors.
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*/
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#include <config.h>
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#include "rand.h"
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#include "rng.h"
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#include <assert.h>
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#include <string.h>
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#include <math.h>
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#include <float.h>
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#include <ctype.h>
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#define M_PIl 3.1415926535897932384626433832795029L /* pi */
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/* NormalRand aus python, random.py geklaut, dort ist Referenz auf
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* den Algorithmus. mu = Mittelwert, sigma = Standardabweichung. */
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double
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normalvariate(double mu, double sigma)
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{
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static double NV_MAGICCONST = 1.7155277699214135;
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double z;
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for (;;) {
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double u1 = rng_double();
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double u2 = 1.0 - rng_double();
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z = NV_MAGICCONST*(u1-0.5)/u2;
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if (z*z/4.0 <= -log(u2)) {
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break;
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}
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}
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return mu+z*sigma;
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}
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int
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ntimespprob(int n, double p, double mod)
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{
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int count = 0;
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int i;
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for(i=0; i<n && p>0; i++) {
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if(rng_double() < p) {
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count++;
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p += mod;
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}
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}
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return count;
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}
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boolean
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chance(double x)
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{
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if (x>=1.0) return true;
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return rng_double() < x;
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}
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