NAME
y0, y0f, y0l, y1, y1f, y1l, yn, ynf, ynl - Bessel functions of the
second kind
SYNOPSIS
#include <math.h>
double y0(double x);
double y1(double x);
double yn(int n, double x);
float y0f(float x);
float y1f(float x);
float ynf(int n, float x);
long double y0l(long double x);
long double y1l(long double x);
long double ynl(int n, long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
y0(), y1(), yn(): _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE
y0f(), y0l(), y1f(), y1l(), ynf(), ynl(): _SVID_SOURCE || _BSD_SOURCE
|| _XOPEN_SOURCE >= 600
DESCRIPTION
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.
The value of x must be positive.
The y0f() etc. and y0l() etc. functions are versions that take and
return float and long double values, respectively.
RETURN VALUE
On success, these functions return the appropriate Bessel value of the
second kind for x.
If x is a NaN, a NaN is returned.
If x is negative, a domain error occurs, and the functions return
-HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively. (POSIX.1-2001 also
allows a NaN return for this case.)
If x is 0.0, a pole error occurs, and the functions return -HUGE_VAL,
-HUGE_VALF, or -HUGE_VALL, respectively.
If the result underflows, a range error occurs, and the functions
return 0.0
If the result overflows, a range error occurs, and the functions return
-HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively. (POSIX.1-2001 also
allows a 0.0 return for this case.)
ERRORS
See math_error(7) for information on how to determine whether an error
has occurred when calling these functions.
The following errors can occur:
Domain error: x is negative
errno is set to EDOM. An invalid floating-point exception
(FE_INVALID) is raised.
Pole error: x is 0.0
errno is set to ERANGE (but see BUGS). No FE_DIVBYZERO
exception is returned by fetestexcept(3) for this case.
Range error: result underflow
errno is set to ERANGE. No FE_UNDERFLOW exception is returned
by fetestexcept(3) for this case.
Range error: result overflow
errno is not set for this case. An overflow floating-point
exception (FE_OVERFLOW) is raised.
CONFORMING TO
The functions returning double conform to SVr4, 4.3BSD, POSIX.1-2001.
The others are nonstandard functions that also exist on the BSDs.
BUGS
On a pole error, these functions set errno to EDOM, instead of ERANGE
as POSIX.1-2004 requires.
In glibc version 2.3.2 and earlier, these functions do not raise an
invalid floating-point exception (FE_INVALID) when a domain error
occurs.
SEE ALSO
j0(3)
COLOPHON
This page is part of release 3.24 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2008-08-10