Abdelrahman Said
166 lines
6.6 KiB
C
166 lines
6.6 KiB
C
/*
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igraph library.
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Copyright (C) 2003-2025 The igraph development team <igraph@igraph.org>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef IGRAPH_RANDOM_H
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#define IGRAPH_RANDOM_H
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#include "igraph_decls.h"
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#include "igraph_error.h"
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#include "igraph_types.h"
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#include <stdint.h>
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#include <stdlib.h>
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IGRAPH_BEGIN_C_DECLS
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/* The new RNG interface is (somewhat) modelled on the GSL */
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/* When implementing your own RNG in igraph, the following methods must be
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* supplied in the corresponding igraph_rng_type_t structure:
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*
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* - init()
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* - destroy()
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* - seed()
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* - get()
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*
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* Optionally, you can provide specialized routines for several distributions
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* in the following functions:
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*
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* - get_int()
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* - get_real()
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* - get_norm()
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* - get_geom()
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* - get_binom()
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* - get_exp()
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* - get_gamma()
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* - get_pois()
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*
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* The best is probably to define get() leave the others as NULL; igraph will use
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* default implementations for these.
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*
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* Note that if all that you would do in a get_real() implementation is to
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* generate random bits with get() and divide by the maximum, don't do that;
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* The default implementation takes care of calling get() a sufficient number of
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* times to utilize most of the precision of the igraph_real_t type, and generate
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* accurate variates. Inaccuracies in the output of get_real() can get magnified
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* when using the default generators for non-uniform distributions.
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* When implementing get_real(), the sampling range must be half-open, i.e. [0, 1).
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* If unsure, leave get_real() unimplemented and igraph will provide an implementation
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* in terms of get().
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*
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* When implementing get_int(), you do not need to check whether lo < hi;
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* the caller is responsible for ensuring that this is the case. You can always
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* assume that hi > lo. Note that both endpoints are _inclusive_, and you must
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* make sure that your generation scheme works for both 32-bit and 64-bit
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* versions of igraph_int_t as igraph can be compiled for both cases. If
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* you are unsure, leave get_int() unimplemented and igraph will provide its
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* own implementation based on get().
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*/
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typedef struct igraph_rng_type_t {
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const char *name;
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uint8_t bits;
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/* Initialization and destruction */
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igraph_error_t (*init)(void **state);
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void (*destroy)(void *state);
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/* Seeding */
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igraph_error_t (*seed)(void *state, igraph_uint_t seed);
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/* Fundamental generator: return as many random bits as the RNG supports in
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* a single round */
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igraph_uint_t (*get)(void *state);
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/* Optional generators; defaults are provided by igraph that rely solely
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* on get() */
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igraph_int_t (*get_int)(void *state, igraph_int_t l, igraph_int_t h);
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igraph_real_t (*get_real)(void *state);
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igraph_real_t (*get_norm)(void *state);
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igraph_real_t (*get_geom)(void *state, igraph_real_t p);
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igraph_real_t (*get_binom)(void *state, igraph_int_t n, igraph_real_t p);
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igraph_real_t (*get_exp)(void *state, igraph_real_t rate);
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igraph_real_t (*get_gamma)(void *state, igraph_real_t shape,
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igraph_real_t scale);
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igraph_real_t (*get_pois)(void *state, igraph_real_t mu);
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} igraph_rng_type_t;
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typedef struct igraph_rng_t {
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const igraph_rng_type_t *type;
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void *state;
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igraph_bool_t is_seeded;
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} igraph_rng_t;
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/* --------------------------------- */
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IGRAPH_EXPORT igraph_error_t igraph_rng_init(igraph_rng_t *rng, const igraph_rng_type_t *type);
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IGRAPH_EXPORT void igraph_rng_destroy(igraph_rng_t *rng);
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IGRAPH_EXPORT igraph_error_t igraph_rng_seed(igraph_rng_t *rng, igraph_uint_t seed);
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IGRAPH_EXPORT IGRAPH_FUNCATTR_PURE igraph_int_t igraph_rng_bits(const igraph_rng_t* rng);
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IGRAPH_EXPORT IGRAPH_FUNCATTR_PURE igraph_uint_t igraph_rng_max(const igraph_rng_t *rng);
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IGRAPH_EXPORT IGRAPH_FUNCATTR_PURE const char *igraph_rng_name(const igraph_rng_t *rng);
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IGRAPH_EXPORT igraph_bool_t igraph_rng_get_bool(igraph_rng_t *rng) ;
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IGRAPH_EXPORT igraph_int_t igraph_rng_get_integer(
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igraph_rng_t *rng, igraph_int_t l, igraph_int_t h
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);
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IGRAPH_EXPORT igraph_real_t igraph_rng_get_normal(
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igraph_rng_t *rng, igraph_real_t m, igraph_real_t s
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);
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IGRAPH_EXPORT igraph_real_t igraph_rng_get_unif(
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igraph_rng_t *rng, igraph_real_t l, igraph_real_t h
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);
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IGRAPH_EXPORT igraph_real_t igraph_rng_get_unif01(igraph_rng_t *rng);
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IGRAPH_EXPORT igraph_real_t igraph_rng_get_geom(igraph_rng_t *rng, igraph_real_t p);
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IGRAPH_EXPORT igraph_real_t igraph_rng_get_binom(
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igraph_rng_t *rng, igraph_int_t n, igraph_real_t p
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);
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IGRAPH_EXPORT igraph_real_t igraph_rng_get_exp(igraph_rng_t *rng, igraph_real_t rate);
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IGRAPH_EXPORT igraph_real_t igraph_rng_get_gamma(
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igraph_rng_t *rng, igraph_real_t shape, igraph_real_t scale
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);
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IGRAPH_EXPORT igraph_real_t igraph_rng_get_pois(igraph_rng_t *rng, igraph_real_t rate);
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/* --------------------------------- */
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IGRAPH_EXPORT extern const igraph_rng_type_t igraph_rngtype_glibc2;
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IGRAPH_EXPORT extern const igraph_rng_type_t igraph_rngtype_mt19937;
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IGRAPH_EXPORT extern const igraph_rng_type_t igraph_rngtype_pcg32;
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IGRAPH_EXPORT extern const igraph_rng_type_t igraph_rngtype_pcg64;
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IGRAPH_EXPORT igraph_rng_t *igraph_rng_default(void);
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IGRAPH_EXPORT igraph_rng_t *igraph_rng_set_default(igraph_rng_t *rng);
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/* --------------------------------- */
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#define RNG_BOOL() (igraph_rng_get_bool(igraph_rng_default()))
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#define RNG_INTEGER(l,h) (igraph_rng_get_integer(igraph_rng_default(),(l),(h)))
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#define RNG_NORMAL(m,s) (igraph_rng_get_normal(igraph_rng_default(),(m),(s)))
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#define RNG_UNIF(l,h) (igraph_rng_get_unif(igraph_rng_default(),(l),(h)))
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#define RNG_UNIF01() (igraph_rng_get_unif01(igraph_rng_default()))
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#define RNG_GEOM(p) (igraph_rng_get_geom(igraph_rng_default(),(p)))
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#define RNG_BINOM(n,p) (igraph_rng_get_binom(igraph_rng_default(),(n),(p)))
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#define RNG_EXP(rate) (igraph_rng_get_exp(igraph_rng_default(),(rate)))
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#define RNG_POIS(rate) (igraph_rng_get_pois(igraph_rng_default(),(rate)))
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#define RNG_GAMMA(shape, scale) \
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(igraph_rng_get_gamma(igraph_rng_default(), (shape), (scale)))
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IGRAPH_END_C_DECLS
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#endif
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