distrib.h

//==========================================================================
// DISTRIB.H
//
//                     OMNeT++/OMNEST
//            Discrete System Simulation in C++
//
// Random variate generation
//
// Authors: Werner Sandmann (ws), Kay Michael Masslow (kmm), Kyeong Soo (Joseph) Kim (jk)
// Documentation, maintenance: Andras Varga
//
// @date 11/26/2002 "doxygenification" (kmm)
// @date 11/20/2002 some final comments (ws)
// @date 10/22/2002 implemented various discrete distributions (kmm)
//
//==========================================================================


#ifndef __DISTRIB_H_
#define __DISTRIB_H_

#include "simkerneldefs.h"
#include "random.h"
#include "simtime.h"

NAMESPACE_BEGIN


SIM_API double uniform(double a, double b, int rng=0);

inline SimTime uniform(SimTime a, SimTime b, int rng=0) {return uniform(a.dbl(), b.dbl(), rng);}

SIM_API double exponential(double mean, int rng=0);

inline SimTime exponential(SimTime mean, int rng=0) {return exponential(mean.dbl(), rng);}

SIM_API double normal(double mean, double stddev, int rng=0);

inline SimTime normal(SimTime mean, SimTime stddev, int rng=0) {return normal(mean.dbl(), stddev.dbl(), rng);}

SIM_API double truncnormal(double mean, double stddev, int rng=0);

inline SimTime truncnormal(SimTime mean, SimTime stddev, int rng=0) {return truncnormal(mean.dbl(), stddev.dbl(), rng);}

SIM_API double gamma_d(double alpha, double theta, int rng=0);

SIM_API double beta(double alpha1, double alpha2, int rng=0);

SIM_API double erlang_k(unsigned int k, double mean, int rng=0);

SIM_API double chi_square(unsigned int k, int rng=0);

SIM_API double student_t(unsigned int i, int rng=0);

SIM_API double cauchy(double a, double b, int rng=0);

SIM_API double triang(double a, double b, double c, int rng=0);

inline double lognormal(double m, double w, int rng=0)
{
    return exp(normal(m, w, rng));
}

SIM_API double weibull(double a, double b, int rng=0);

SIM_API double pareto_shifted(double a, double b, double c, int rng=0);



SIM_API int intuniform(int a, int b, int rng=0);

inline int bernoulli(double p, int rng=0)
{
    double U = genk_dblrand(rng);
    return (p > U) ? 1 : 0;
}

SIM_API int binomial(int n, double p, int rng=0);

SIM_API int geometric(double p, int rng=0);

SIM_API int negbinomial(int n, double p, int rng=0);

//
// hypergeometric() doesn't work yet
//
// /* *
//  * Returns a random integer from the hypergeometric distribution with
//  * parameters a,b and n.
//  *
//  * If you have a+b items (a items of type A and b items of type B)
//  * and you draw n items from them without replication, this function
//  * will return the number of type A items in the drawn set.
//  *
//  * Generation uses inverse transform due to Fishman (see Banks, page 165).
//  *
//  * @param a, b  a,b>0
//  * @param n     0<=n<=a+b
//  * @param rng the underlying random number generator
//  */
// SIM_API int hypergeometric(int a, int b, int n, int rng=0);

SIM_API int poisson(double lambda, int rng=0);


NAMESPACE_END


#endif