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.
10

NAME

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

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

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

32       Upon  successful  completion, these functions shall return the relevant
33       Bessel value of x of the second kind.
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35       If x is NaN, NaN shall be returned.
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37       If the x argument to these functions  is  negative,  -HUGE_VAL  or  NaN
38       shall be returned, and a domain error may occur.
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40       If x is 0.0, -HUGE_VAL shall be returned and a pole error may occur.
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42       If  the correct result would cause underflow, 0.0 shall be returned and
43       a range error may occur.
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45       If the correct result would cause overflow, -HUGE_VAL or 0.0  shall  be
46       returned and a range error may occur.
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ERRORS

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

88       None.
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APPLICATION USAGE

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

96       None.
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FUTURE DIRECTIONS

99       None.
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SEE ALSO

102       feclearexcept(), fetestexcept(), isnan(), j0()
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104       The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of
105       Error Conditions for Mathematical Functions, <math.h>
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108       Portions  of  this text are reprinted and reproduced in electronic form
109       from IEEE Std 1003.1-2017, Standard for Information Technology --  Por‐
110       table  Operating System Interface (POSIX), The Open Group Base Specifi‐
111       cations Issue 7, 2018 Edition, Copyright (C) 2018 by the  Institute  of
112       Electrical  and  Electronics Engineers, Inc and The Open Group.  In the
113       event of any discrepancy between this version and the original IEEE and
114       The  Open Group Standard, the original IEEE and The Open Group Standard
115       is the referee document. The original Standard can be  obtained  online
116       at http://www.opengroup.org/unix/online.html .
117
118       Any  typographical  or  formatting  errors that appear in this page are
119       most likely to have been introduced during the conversion of the source
120       files  to  man page format. To report such errors, see https://www.ker‐
121       nel.org/doc/man-pages/reporting_bugs.html .
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125IEEE/The Open Group                  2017                               Y0(3P)
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