#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "filter.h"

#ifdef WIN
double drand48()
{
	return (double)rand()/(double)RAND_MAX;
}
void srand48(long seed)
{
	srand(seed);
}
#endif

/*	uniform distribution random number		*/
/*	between a and b					*/

extern double uniformrand(double a, double b)
{
	return (b-a)*drand48() + a;
}

/*	normal distribution randam number N(0,1)	*/
/*	average \mu = 0 and variance \rho^2 = 1		*/

extern double nrand(void)
{
	double	sum, f;
	int	k;
	
	sum = 0.00;
	for (k=0; k<12; k++) {
		f = drand48();	/* uniform random [0,1) */
		sum += f;
	}
	sum -= 6;
	
	return sum;
}

/*	normal distribution randam number N(mu,rho^2)	*/
/*	with average mu and variance rho^2		*/

extern double normalrand(double mu, double var)
{
	return var * nrand() + mu;
}

/*	exponential distribution random number	*/

extern double exponetialrand(double lambda)
{
	return (- log(- drand48())/lambda);
}