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.TH Y0 "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"

.SH PROLOG

This manual page is part of the POSIX Programmer's Manual.

The Linux implementation of this interface may differ (consult

the corresponding Linux manual page for details of Linux behavior),

or the interface may not be implemented on Linux.

.SH NAME

y0,

y1,

yn

\(em Bessel functions of the second kind

.SH SYNOPSIS

.LP

.nf

#include <math.h>

.P

double y0(double \fIx\fP);

double y1(double \fIx\fP);

double yn(int \fIn\fP, double \fIx\fP);

.fi

.SH DESCRIPTION

The

\fIy0\fR(),

\fIy1\fR(),

and

\fIyn\fR()

functions shall compute Bessel functions of

.IR x

of the second kind of orders 0, 1, and

.IR n ,

respectively.

.P

An application wishing to check for error situations should set

.IR errno

to zero and call

.IR feclearexcept (FE_ALL_EXCEPT)

before calling these functions. On return, if

.IR errno

is non-zero or \fIfetestexcept\fR(FE_INVALID | FE_DIVBYZERO |

FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.

.SH "RETURN VALUE"

Upon successful completion, these functions shall return the relevant

Bessel value of

.IR x

of the second kind.

.P

If

.IR x

is NaN, NaN shall be returned.

.P

If the

.IR x

argument to these functions is negative, \(miHUGE_VAL or NaN shall be

returned, and a domain error may occur.

.P

If

.IR x

is 0.0, \(miHUGE_VAL shall be returned and a pole error may occur.

.P

If the correct result would cause underflow, 0.0 shall be returned and

a range error may occur.

.P

If the correct result would cause overflow, \(miHUGE_VAL or 0.0 shall

be returned and a range error may occur.

.SH ERRORS

These functions may fail if:

.IP "Domain\ Error" 12

The value of

.IR x

is negative.

.RS 12 

.P

If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is

non-zero, then

.IR errno

shall be set to

.BR [EDOM] .

If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is

non-zero, then the invalid floating-point exception shall be raised.

.RE

.IP "Pole\ Error" 12

The value of

.IR x

is zero.

.RS 12 

.P

If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is

non-zero, then

.IR errno

shall be set to

.BR [ERANGE] .

If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is

non-zero, then the divide-by-zero floating-point exception shall be

raised.

.RE

.IP "Range\ Error" 12

The correct result would cause overflow.

.RS 12 

.P

If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is

non-zero, then

.IR errno

shall be set to

.BR [ERANGE] .

If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is

non-zero, then the overflow floating-point exception shall be raised.

.RE

.IP "Range\ Error" 12

The value of

.IR x

is too large in magnitude, or the correct result would cause

underflow.

.RS 12 

.P

If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is

non-zero, then

.IR errno

shall be set to

.BR [ERANGE] .

If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is

non-zero, then the underflow floating-point exception shall be raised.

.RE

.LP

.IR "The following sections are informative."

.SH EXAMPLES

None.

.SH "APPLICATION USAGE"

On error, the expressions (\fImath_errhandling\fR & MATH_ERRNO) and

(\fImath_errhandling\fR & MATH_ERREXCEPT) are independent of each

other, but at least one of them must be non-zero.

.SH RATIONALE

None.

.SH "FUTURE DIRECTIONS"

None.

.SH "SEE ALSO"

.IR "\fIfeclearexcept\fR\^(\|)",

.IR "\fIfetestexcept\fR\^(\|)",

.IR "\fIisnan\fR\^(\|)",

.IR "\fIj0\fR\^(\|)"

.P

The Base Definitions volume of POSIX.1\(hy2008,

.IR "Section 4.19" ", " "Treatment of Error Conditions for Mathematical Functions",

.IR "\fB<math.h>\fP"

.SH COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form

from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology

-- Portable Operating System Interface (POSIX), The Open Group Base

Specifications Issue 7, Copyright (C) 2013 by the Institute of

Electrical and Electronics Engineers, Inc and The Open Group.

(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

Any typographical or formatting errors that appear

in this page are most likely

to have been introduced during the conversion of the source files to

man page format. To report such errors, see

https://www.kernel.org/doc/man-pages/reporting_bugs.html .