#include "random.h"
#include <math.h>
double randn(void)
{
/* Generates a random number from a normal distribution using the
* Box-Muller transform. */
double u1, u2;
u1 = genrand_real1();
u2 = genrand_real1();
return sqrt(-2*log(u1))*cos(2*M_PI*u2);
}