# DragonFly On-Line Manual Pages

```J0(3)		      DragonFly 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

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() and j1() compute the Bessel function of the first kind
of the order 0 and the order 1, respectively, for the real value x; the
function jn() computes the Bessel function of the first kind of the
integer order n for the real value x.  The functions j0f(), j1f(), and
jnf() are single precision versions of j0(), j1(), and jn(), respec-
tively.

The functions y0() and y1() compute the linearly independent Bessel
function of the second kind of the order 0 and the order 1, respectively,
for the positive integer value x (expressed as a double); the function
yn() computes the Bessel function of the second kind for the integer
order n for the positive integer value x (expressed as a double).	The
functions y0f(), y1f(), and ynf() are single precision versions of y0(),
y1(), and yn(), respectively.

RETURN VALUES
If these functions are successful, the computed value is returned, other-
wise the global variable errno is set to EDOM or ERANGE.

HISTORY
The functions j0(), j1(), jn(), y0(), y1(), and yn() first appeared in
Version 7 AT&T UNIX.

DragonFly 4.3			 July 17, 2013			 DragonFly 4.3
```