y1(3) - c7

1Y0(3)                      Linux Programmer's Manual                     Y0(3)
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NAME

6       y0, y0f, y0l, y1, y1f, y1l, yn, ynf, ynl - Bessel functions of the sec‐
7       ond kind
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SYNOPSIS

10       #include <math.h>
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12       double y0(double x);
13       double y1(double x);
14       double yn(int n, double x);
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16       float y0f(float x);
17       float y1f(float x);
18       float ynf(int n, float x);
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20       long double y0l(long double x);
21       long double y1l(long double x);
22       long double ynl(int n, long double x);
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24       Link with -lm.
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26   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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28       y0(), y1(), yn():
29           _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE
30       y0f(), y0l(), y1f(), y1l(), ynf(), ynl():
31           _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 600
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DESCRIPTION

34       The y0() and y1() functions return Bessel functions of x of the  second
35       kind  of  orders  0 and 1, respectively.  The yn() function returns the
36       Bessel function of x of the second kind of order n.
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38       The value of x must be positive.
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40       The y0f() etc. and y0l() etc. functions  are  versions  that  take  and
41       return float and long double values, respectively.
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RETURN VALUE

44       On  success, these functions return the appropriate Bessel value of the
45       second kind for x.
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47       If x is a NaN, a NaN is returned.
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49       If x is negative, a domain  error  occurs,  and  the  functions  return
50       -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively.  (POSIX.1-2001 also
51       allows a NaN return for this case.)
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53       If x is 0.0, a pole error occurs, and the functions  return  -HUGE_VAL,
54       -HUGE_VALF, or -HUGE_VALL, respectively.
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56       If  the  result  underflows,  a  range  error occurs, and the functions
57       return 0.0
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59       If the result overflows, a range error occurs, and the functions return
60       -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively.  (POSIX.1-2001 also
61       allows a 0.0 return for this case.)
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ERRORS

64       See math_error(7) for information on how to determine whether an  error
65       has occurred when calling these functions.
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67       The following errors can occur:
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69       Domain error: x is negative
70              errno  is  set  to  EDOM.   An  invalid floating-point exception
71              (FE_INVALID) is raised.
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73       Pole error: x is 0.0
74              errno is set to ERANGE (but see BUGS).  No  FE_DIVBYZERO  excep‐
75              tion is returned by fetestexcept(3) for this case.
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77       Range error: result underflow
78              errno  is  set to ERANGE.  No FE_UNDERFLOW exception is returned
79              by fetestexcept(3) for this case.
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81       Range error: result overflow
82              errno is not set for  this  case.   An  overflow  floating-point
83              exception (FE_OVERFLOW) is raised.
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CONFORMING TO

86       The  functions  returning double conform to SVr4, 4.3BSD, POSIX.1-2001.
87       The others are nonstandard functions that also exist on the BSDs.
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BUGS

90       On a pole error, these functions set errno to EDOM, instead  of  ERANGE
91       as POSIX.1-2004 requires.
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93       In  glibc  version  2.3.2  and earlier, these functions do not raise an
94       invalid floating-point  exception  (FE_INVALID)  when  a  domain  error
95       occurs.
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COLOPHON

101       This  page  is  part of release 3.53 of the Linux man-pages project.  A
102       description of the project, and information about reporting  bugs,  can
103       be found at http://www.kernel.org/doc/man-pages/.
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107                                  2008-08-10                             Y0(3)