y0, y1, yn - Bessel functions of the second kind

Definition	#include <math.h> double y0(double x); double y1(double x); double yn(int n, double x); The functions y0, y1 and yn calculate the Bessel functions of the second kind for real arguments x and the integer orders 0, 1 or n.
Return val.	Bessel function for the real argument x > 0.
	-HUGE_VAL	for arguments ≤ 0. In addition, errno is set to EDOM (domain error, i.e invalid argument).
See also	j0, j1, jn