freebsd man page for y1

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

NAME
     j0, j0f, j1, j1f, jn, jnf, y0, y0f, y1, y1f, yn, ynf -- Bessel functions of first and second kind

LIBRARY
     Math Library (libm, -lm)

SYNOPSIS
     #include <math.h>

     double
     j0(double x);

     float
     j0f(float x);

     double
     j1(double x);

     float
     j1f(float x);

     double
     jn(int n, double x);

     float
     jnf(int n, float x);

     double
     y0(double x);

     float
     y0f(float x);

     double
     y1(double x);

     float
     y1f(float x);

     double
     yn(int n, double x);

     float
     ynf(int n, float x);

DESCRIPTION
     The functions j0(), j0f(), j1() and j1f() compute the Bessel function of the first kind of the order 0 and the order 1, respectively, for the
     real value x; the functions jn() and jnf() compute the Bessel function of the first kind of the integer order n for the real value x.

     The functions y0(), y0f(), y1(), and y1f() compute the linearly independent Bessel function of the second kind of the order 0 and the order
     1, respectively, for the positive real value x; the functions yn() and ynf() compute the Bessel function of the second kind for the integer
     order n for the positive real value x.

RETURN VALUES
     These routines return values of their respective Bessel functions.  For large positive inputs, they may underflow and return +-0.

     The following applies to y0(), y0f(), y1(), y1f(), yn(), and ynf().  If x is negative, these routines will generate an invalid exception and
     return NaN.  If x is 0 or a sufficiently small positive number, these routines will generate an overflow exception and return -infinity.

SEE ALSO
     math(3)

STANDARDS
     The j0(), j1(), jn(), y0(), y1(), and yn() functions conform to IEEE Std 1003.1-2001 (``POSIX.1'').  The float versions are extensions.

HISTORY
     This set of functions appeared in Version 7 AT&T UNIX.

BSD
								 February 18, 2008							       BSD