/*Create a random number from N(0,1)*/
#include "math.h"
double rnorm(int *idum)
{
static int iset=0;
static double gset;
double fac, r, v1, v2;
double ran1(int *idum);
if (iset==0) {
do {
v1=2.0*ran1(idum)-1.0;
v2=2.0*ran1(idum)-1.0;
r=v1*v1+v2*v2;
}while (r>=1.0 || r==0.0);
fac=sqrt(-2.0*log(r)/r);
gset=v1*fac;
iset=1;
return v2*fac;
}
else {
iset=0;
return gset;
}
}