forked from github/server
131 lines
3.1 KiB
C
131 lines
3.1 KiB
C
/*
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Copyright (c) 1998-2015, Enno Rehling <enno@eressea.de>
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Katja Zedel <katze@felidae.kn-bremen.de
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Christian Schlittchen <corwin@amber.kn-bremen.de>
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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**/
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#include <platform.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 <stdlib.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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/* NormalRand aus python, random.py geklaut, dort ist Referenz auf
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* den Algorithmus. mu = Mittelwert, sigma = Standardabweichung.
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* http://de.wikipedia.org/wiki/Standardabweichung#Diskrete_Gleichverteilung.2C_W.C3.BCrfel
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*/
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double normalvariate(double mu, double sigma)
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{
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static const double NV_MAGICCONST = 1.7155277699214135; /* STATIC_CONST: a constant */
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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 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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bool chance(double x)
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{
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if (x >= 1.0)
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return true;
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return rng_double() < x;
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}
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extern double genrand_real2(void);
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typedef struct random_source {
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double (*double_source) (void);
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} random_source;
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random_source *r_source = 0;
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double rng_injectable_double(void) {
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if (r_source)
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return r_source->double_source();
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return genrand_real2();
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}
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static double constant_value;
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static double constant_source (void) {
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return constant_value;
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}
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struct random_source constant_provider = {
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constant_source
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};
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void random_source_inject_constant(double value) {
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constant_value = value;
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r_source = &constant_provider;
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}
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static int i = 0;
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static double *values;
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static int value_size = 0;
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static double array_source (void) {
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assert(i<value_size);
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return values[i++];
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}
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struct random_source array_provider = {
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array_source
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};
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void random_source_inject_array(double inject[], int size) {
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assert(size > 0);
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value_size = size;
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if (values)
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free(values);
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values = malloc(sizeof(double) * size);
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for (i=0; i < size; ++i) {
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values[i] = inject[i];
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}
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i = 0;
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r_source = &array_provider;
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}
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void random_source_reset(void) {
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if (values)
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free(values);
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values = NULL;
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r_source = NULL;
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}
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