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

Syntax	#include <math.h> double y0(double x); double y1(double x); double yn(int n, double x);
Description	y0(), y1() and yn() compute the Bessel functions of the second kind for real arguments x (> 0) and the integral orders 0, 1 or n (only for yn).
Return val.	Value of the Bessel function of x, if x >0.
	-HUGE_VAL	for arguments ≤ 0. errno is set to indicate the error.
Errors	y0(), y1() and yn() will fail if: EDOM        The value of x is negative.
See also	j0(), j1(), jn(), math.h.