1Y0(3P)                     POSIX Programmer's Manual                    Y0(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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11

NAME

13       y0, y1, yn — Bessel functions of the second kind
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SYNOPSIS

16       #include <math.h>
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18       double y0(double x);
19       double y1(double x);
20       double yn(int n, double x);
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DESCRIPTION

23       The y0(), y1(), and yn() functions shall compute Bessel functions of  x
24       of the second kind of orders 0, 1, and n, respectively.
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26       An  application  wishing to check for error situations should set errno
27       to zero and  call  feclearexcept(FE_ALL_EXCEPT)  before  calling  these
28       functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
29       FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero,  an  error  has
30       occurred.
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RETURN VALUE

33       Upon  successful  completion, these functions shall return the relevant
34       Bessel value of x of the second kind.
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36       If x is NaN, NaN shall be returned.
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38       If the x argument to these functions  is  negative,  −HUGE_VAL  or  NaN
39       shall be returned, and a domain error may occur.
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41       If x is 0.0, −HUGE_VAL shall be returned and a pole error may occur.
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43       If  the correct result would cause underflow, 0.0 shall be returned and
44       a range error may occur.
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46       If the correct result would cause overflow, −HUGE_VAL or 0.0  shall  be
47       returned and a range error may occur.
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ERRORS

50       These functions may fail if:
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52       Domain Error
53                   The value of x is negative.
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55                   If  the  integer expression (math_errhandling & MATH_ERRNO)
56                   is non-zero, then errno shall be set  to  [EDOM].   If  the
57                   integer  expression  (math_errhandling & MATH_ERREXCEPT) is
58                   non-zero, then the invalid floating-point  exception  shall
59                   be raised.
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61       Pole Error  The value of x is zero.
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63                   If  the  integer expression (math_errhandling & MATH_ERRNO)
64                   is non-zero, then errno shall be set to [ERANGE].   If  the
65                   integer  expression  (math_errhandling & MATH_ERREXCEPT) is
66                   non-zero, then the divide-by-zero floating-point  exception
67                   shall be raised.
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69       Range Error The correct result would cause overflow.
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71                   If  the  integer expression (math_errhandling & MATH_ERRNO)
72                   is non-zero, then errno shall be set to [ERANGE].   If  the
73                   integer  expression  (math_errhandling & MATH_ERREXCEPT) is
74                   non-zero, then the overflow floating-point exception  shall
75                   be raised.
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77       Range Error The  value  of  x is too large in magnitude, or the correct
78                   result would cause underflow.
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80                   If the integer expression (math_errhandling  &  MATH_ERRNO)
81                   is  non-zero,  then errno shall be set to [ERANGE].  If the
82                   integer expression (math_errhandling &  MATH_ERREXCEPT)  is
83                   non-zero, then the underflow floating-point exception shall
84                   be raised.
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86       The following sections are informative.
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EXAMPLES

89       None.
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APPLICATION USAGE

92       On  error,  the  expressions  (math_errhandling   &   MATH_ERRNO)   and
93       (math_errhandling  & MATH_ERREXCEPT) are independent of each other, but
94       at least one of them must be non-zero.
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RATIONALE

97       None.
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FUTURE DIRECTIONS

100       None.
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SEE ALSO

103       feclearexcept(), fetestexcept(), isnan(), j0()
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105       The Base Definitions volume of POSIX.1‐2008, Section 4.19, Treatment of
106       Error Conditions for Mathematical Functions, <math.h>
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109       Portions  of  this text are reprinted and reproduced in electronic form
110       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
111       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
112       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
113       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
114       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
115       event of any discrepancy between this version and the original IEEE and
116       The Open Group Standard, the original IEEE and The Open Group  Standard
117       is  the  referee document. The original Standard can be obtained online
118       at http://www.unix.org/online.html .
119
120       Any typographical or formatting errors that appear  in  this  page  are
121       most likely to have been introduced during the conversion of the source
122       files to man page format. To report such errors,  see  https://www.ker‐
123       nel.org/doc/man-pages/reporting_bugs.html .
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127IEEE/The Open Group                  2013                               Y0(3P)
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