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Y0
Section: Linux Programmer's Manual (3)
Updated: 20150419
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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(),
y1f(),
and
ynf()
functions are versions that take and return
float
values.
The
y0l(),
y1l(),
and
ynl()
functions are versions that take and return
long double
values.
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.12001 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.12001 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 floatingpoint 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 floatingpoint exception
(FE_OVERFLOW)
is raised.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
Interface  Attribute  Value

y0(),
y0f(),
y0l()
 Thread safety  MTSafe

y1(),
y1f(),
y1l()
 Thread safety  MTSafe

yn(),
ynf(),
ynl()
 Thread safety  MTSafe

CONFORMING TO
The functions returning
double
conform to SVr4, 4.3BSD,
POSIX.12001, POSIX.12008.
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.12004 requires.
In glibc version 2.3.2 and earlier,
these functions do not raise an invalid floatingpoint exception
(FE_INVALID)
when a domain error occurs.
SEE ALSO
j0(3)
COLOPHON
This page is part of release 4.04 of the Linux
manpages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
http://www.kernel.org/doc/manpages/.
Index
 NAME

 SYNOPSIS

 DESCRIPTION

 RETURN VALUE

 ERRORS

 ATTRIBUTES

 CONFORMING TO

 BUGS

 SEE ALSO

 COLOPHON

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