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bessel(3)
NAME
  bessel, j0, j1, jn, y0, y1, yn - Compute Bessel functions

LIBRARY
  Math Library (libm.a)

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);

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  j0():	 XPG4

  j1():	 XPG4

  jn():	 XPG4

  y0():	 XPG4

  y1():	 XPG4

  yn():	 XPG4

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

DESCRIPTION
  The j0(), j0f(), j1(), and j1f() functions return the value of the Bessel
  function of the first kind of orders 0 (zero) and 1, respectively.

  The jn() and jnf() functions return the value of the Bessel function of the
  first kind of order n.

  The y0(), y0f(), y1(), and y1f() functions return the value of the Bessel
  functions of the second kind of orders 0 (zero) and 1, respectively.

  The yn() and ynf()  functions return the value of the Bessel function of
  the second kind of order n.

  The following table describes function behavior in response to exceptional
  arguments:

  _____________________________________________________________
  Function		Exceptional Argument   Routine Behavior
  _____________________________________________________________
  j0(), j1(), jn()	None		       N/A
  j0f(), j1f(), jnf()	None		       N/A
  y0(), y1(), yn()	x < 0		       Invalid argument
  y0f(), y1f(), ynf()	x < 0		       Invalid argument
  y0(), y1(), yn()	x = 0		       Overflow
  y0f(), y1f(), ynf()	x = 0		       Overflow
  _____________________________________________________________

  The j1() and jn() functions can result in an underflow as x gets small.
  The largest value of x for which this occurs is a function of n.

  The y1() and yn() functions can result in an overflow as x gets small.  The
  largest value of x for which this occurs is a function of n.