GenRuidoRapido.c

//	Esta funcion genera el "Ruido Blanco Gaussiano" para cada particula
#ifndef GENRUIDORAPIDO_C
#define GENRUIDORAPIDO_C
#include <time.h>
#include <math.h>

// generador standard
#include <stdlib.h>

/*
// generador Alfredo

#include <boost/random/mersenne_twister.hpp>
#include <boost/random/uniform_int.hpp>
#include <boost/random/variate_generator.hpp>


  boost::mt19937 rng;                 // produces randomness out of thin air
                                      // see pseudo-random number generators
  boost::uniform_int<> six(0,256*256*256);  // distribution that maps to 1..6
                                      // see random number distributions
  boost::variate_generator<boost::mt19937&, boost::uniform_int<> >
           irand(rng, six);             // glues randomness with mapping
*/



void GenRuidoRapido(double *Noise, double Sigma, unsigned long int Tmax)
{
  void Gasdev(double *V2, double Sig, long *idum);
  unsigned long int i;
  static long int sem = -1;	//	Semilla para el generador de numeros random.
  if(sem==-1)	sem =-time(NULL);	
  for(i=0; i<Tmax; i+=2) Gasdev(&(Noise[i]), Sigma, &sem);
}

/*
double getrand(void) {
return (double) irand() / (double) (256*256*256);
}
*/

void Gasdev(double *V2, double Sigma, long *idum)
{
  double dran1(long *idum);
  double fac,rsq,v1,v2;
  do {
//	generador stdlib.h [-1,1] 
    v1= 2.0* ((double) rand()/ (double) RAND_MAX )- 1.0;
    v2= 2.0* ((double) rand()/ (double) RAND_MAX )- 1.0;

/*
//	con semilla
    v1=2.0*dran1(idum)-1.0;
    v2=2.0*dran1(idum)-1.0;
*/

/*
//	usando generador Alfredo
    v1=2.0*getrand()-1.0;
    v2=2.0*getrand()-1.0;
*/

    rsq=v1*v1+v2*v2;
  } while (rsq >= 1.0 || rsq == 0.0);
  fac=Sigma*sqrt(-2.0*log(rsq)/rsq);
  V2[0] = v2*fac;
  V2[1] = v1*fac;
}
#endif