Y0(P) POSIX Programmer's Manual Y0(P)NAME
y0, y1, yn - Bessel functions of the second kind
SYNOPSIS
#include <math.h>
double y0(double x);
double y1(double x);
double yn(int n, double x);
DESCRIPTION
The y0(), y1(), and yn() functions shall compute Bessel functions of x
of the second kind of orders 0, 1, and n, respectively.
An application wishing to check for error situations should set errno
to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
functions. On return, if errno is non-zero or fetestexcept(FE_INVALID
| FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
occurred.
RETURN VALUE
Upon successful completion, these functions shall return the relevant
Bessel value of x of the second kind.
If x is NaN, NaN shall be returned.
If the x argument to these functions is negative, -HUGE_VAL or NaN
shall be returned, and a domain error may occur.
If x is 0.0, -HUGE_VAL shall be returned and a range error may occur.
If the correct result would cause underflow, 0.0 shall be returned and
a range error may occur.
If the correct result would cause overflow, -HUGE_VAL or 0.0 shall be
returned and a range error may occur.
ERRORS
These functions may fail if:
Domain Error
The value of x is negative.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
then errno shall be set to [EDOM]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid
floating-point exception shall be raised.
Range Error
The value of x is 0.0, or the correct result would cause over‐
flow.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
then errno shall be set to [ERANGE]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the overflow
floating-point exception shall be raised.
Range Error
The value of x is too large in magnitude, or the correct result
would cause underflow.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
then errno shall be set to [ERANGE]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow
floating-point exception shall be raised.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
On error, the expressions (math_errhandling & MATH_ERRNO) and
(math_errhandling & MATH_ERREXCEPT) are independent of each other, but
at least one of them must be non-zero.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOfeclearexcept() , fetestexcept() , isnan() , j0() , the Base Defini‐
tions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error
Conditions for Mathematical Functions, <math.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 Y0(P)
