osx man page for y1

J0(3)							   BSD Library Functions Manual 						     J0(3)

NAME
     j0, j1, jn, y0, y1, yn -- bessel functions of first and second kind

SYNOPSIS
     #include <math.h>

     double
     j0(double x);

     double
     j1(double x);

     double
     jn(int n, double x);

     double
     y0(double x);

     double
     y1(double x);

     double
     yn(int n, double x);

DESCRIPTION
     The functions j0(x) and j1(x) compute the Bessel function of the first kind of the order 0 and the order 1, respectively; the function jn(n,
     x) computes the Bessel function of the first kind of the integer order n.

     The functions y0(x) and y1(x) compute the linearly independent Bessel function of the second kind of the order 0 and the order 1, respec-
     tively, for the positive integer value x (expressed as a double); the function yn(n, x) computes the Bessel function of the second kind for
     the integer order n for the positive integer value x (expressed as a double).

SPECIAL VALUES
     j0(0) returns 1.

     j0(+-infinity) returns 0.

     j0(NaN) returns a NaN.

     j1(0) returns 0.

     j1(+infinity) returns 0.

     j1(NaN) returns a NaN.

     y0(0) , y1(0) , and yn(n, 0) all return -infinity and raise the "division-by-zero" floating-point flag.

4th Berkeley Distribution					 December 11, 2006					 4th Berkeley Distribution