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manpages-pt-dev_20040726-4_all **NAME**

j0, j1, jn, y0, y1, yn - Bessel functions

**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 **j0()** and **j1()** functions return Bessel functions of __x__ of the first
kind of orders 0 and 1, respectively. The **jn()** function returns the
Bessel function of __x__ of the first kind of order __n__.
The **y0()** and **y1()** functions return Bessel functions of __x__ of the second
kind of orders 0 and 1, respectively. The **yn()** function returns the
Bessel function of __x__ of the second kind of order __n__.
For the functions **y0()**, **y1()** and **yn()**, the value of __x__ must be positive.
For negative values of __x__, these functions return -HUGE_VAL.

**CONFORMING** **TO**

SVID 3, BSD 4.3

**BUGS**

There are errors of up to 2e-16 in the values returned by **j0()**, **j1()**
and **jn()** for values of __x__ between -8 and 8.
June 26, 1993 J0(3)