man pages section 3: Extended Library Functions, Volume 2
Updated: July 2014

y1(3M)

Name

y0, y0f, y0l, y1, y1f, y1l, yn, ynf, ynl - Bessel functions of the second kind

Synopsis

```c99 [ flag... ] file... –lm [ library... ]
#include <math.h>

double y0(double x);```
`float y0f(float x);`
`long double y0l(long double x);`
`double y1(double x);`
`float y1f(float x);`
`long double y1l(long double x);`
`double yn(int n, double x);`
`float ynf(int n, float x);`
`long double ynl(int n, long double x);`

Description

These functions compute Bessel functions of x of the second kind of orders 0, 1 and n, respectively.

Return Values

Upon successful completion, these functions return the relevant Bessel value of x of the second kind.

If x is NaN, a NaN is returned.

If x is negative, −HUGE_VAL or NaN is returned.

If x is 0.0, −HUGE_VAL is returned.

If the correct result would cause overflow, −HUGE_VAL is returned.

For exceptional cases, matherr(3M) tabulates the values to be returned as specified by SVID3 and XPG3.

Errors

No errors are returned.

Usage

An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
MT-Level
MT-Safe
Standard
See below.

For y0(), y1(), and yn(), see standards(5)