# FreeBSD Manual Pages

```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 orders 0	and 1 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 indepen-
dent Bessel function of the second	kind of	orders 0 and 1 for the posi-
tive real value x;	the functions yn() and ynf() compute the Bessel	func-
tion 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, including -infinity, these routines will generate an invalid
exception and return NaN.	If x is	+-0, these routines will generate a
divide-by-zero exception and return -infinity.  If	x is a sufficiently
small positive number, then y1(), y1f(), yn(), and	ynf() 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				March 10, 2015				   BSD
```

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | STANDARDS | HISTORY

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