y0(3p) - f7

1Y0(P)                      POSIX Programmer's Manual                     Y0(P)
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NAME

6       y0, y1, yn - Bessel functions of the second kind
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SYNOPSIS

9       #include <math.h>
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11       double y0(double x);
12       double y1(double x);
13       double yn(int n, double x);
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DESCRIPTION

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

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

44       These functions may fail if:
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46       Domain Error
47              The value of x is negative.
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49       If the integer expression (math_errhandling & MATH_ERRNO) is  non-zero,
50       then   errno  shall  be  set  to  [EDOM].  If  the  integer  expression
51       (math_errhandling &  MATH_ERREXCEPT)  is  non-zero,  then  the  invalid
52       floating-point exception shall be raised.
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54       Range Error
55              The  value  of x is 0.0, or the correct result would cause over‐
56              flow.
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58       If the integer expression (math_errhandling & MATH_ERRNO) is  non-zero,
59       then  errno  shall  be  set  to  [ERANGE].  If  the  integer expression
60       (math_errhandling & MATH_ERREXCEPT)  is  non-zero,  then  the  overflow
61       floating-point exception shall be raised.
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63       Range Error
64              The  value of x is too large in magnitude, or the correct result
65              would cause underflow.
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67       If the integer expression (math_errhandling & MATH_ERRNO) is  non-zero,
68       then  errno  shall  be  set  to  [ERANGE].  If  the  integer expression
69       (math_errhandling & MATH_ERREXCEPT) is  non-zero,  then  the  underflow
70       floating-point exception shall be raised.
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73       The following sections are informative.
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EXAMPLES

76       None.
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APPLICATION USAGE

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

84       None.
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FUTURE DIRECTIONS

87       None.
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COPYRIGHT

95       Portions  of  this text are reprinted and reproduced in electronic form
96       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
97       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
98       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
99       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
100       event of any discrepancy between this version and the original IEEE and
101       The  Open Group Standard, the original IEEE and The Open Group Standard
102       is the referee document. The original Standard can be  obtained  online
103       at http://www.opengroup.org/unix/online.html .
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107IEEE/The Open Group                  2003                                Y0(P)