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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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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21

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 range 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) is non-zero,
56       then  errno  shall  be  set  to  [EDOM].  If  the  integer   expression
57       (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero,  then  the invalid
58       floating-point exception shall be raised.
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60       Range Error
61              The value of x is 0.0, or the correct result would  cause  over‐
62              flow.
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64       If  the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
65       then errno  shall  be  set  to  [ERANGE].  If  the  integer  expression
66       (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero,  then the overflow
67       floating-point exception shall be raised.
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69       Range Error
70              The value of x is too large in magnitude, or the correct  result
71              would cause underflow.
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73       If  the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
74       then errno  shall  be  set  to  [ERANGE].  If  the  integer  expression
75       (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero, then the underflow
76       floating-point exception shall be raised.
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79       The following sections are informative.
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EXAMPLES

82       None.
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APPLICATION USAGE

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

90       None.
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FUTURE DIRECTIONS

93       None.
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SEE ALSO

96       feclearexcept(), fetestexcept(), isnan(), j0(),  the  Base  Definitions
97       volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Condi‐
98       tions for Mathematical Functions, <math.h>
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101       Portions of this text are reprinted and reproduced in  electronic  form
102       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
103       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
104       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
105       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
106       event of any discrepancy between this version and the original IEEE and
107       The Open Group Standard, the original IEEE and The Open Group  Standard
108       is  the  referee document. The original Standard can be obtained online
109       at http://www.opengroup.org/unix/online.html .
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113IEEE/The Open Group                  2003                               Y0(3P)
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