double f_noedge(               /* Calculates G(r) without edge correction */
		coord *points, /* An array of positions */
		coord *events, /* An array of events (same length as points) */
		int n,               /* Number of points */
		double r);           /* Parameter of g */

double f_tor(              /* Calculates G(r) on a torus */
	     coord *points,  /* An array of positions */
	     coord *events,  /* An array of events (same length as points) */
	     int n,               /* Number of points */
	     double a,            /* Length of box in x-direction */
	     double b,            /* Length of box in y-direction */
	     double r);           /* Parameter of g */
