1J0(3P)                     POSIX Programmer's Manual                    J0(3P)
2
3
4

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       j0, j1, jn - Bessel functions of the first kind
13

SYNOPSIS

15       #include <math.h>
16
17       double j0(double x);
18       double j1(double x);
19       double jn(int n, double x);
20
21

DESCRIPTION

23       The j0(), j1(), and jn() functions shall compute Bessel functions of  x
24       of the first kind of orders 0, 1, and n, respectively.
25
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.
31

RETURN VALUE

33       Upon  successful  completion, these functions shall return the relevant
34       Bessel value of x of the first kind.
35
36       If the x argument is too large in  magnitude,  or  the  correct  result
37       would cause underflow, 0 shall be returned and a range error may occur.
38
39       If x is NaN, a NaN shall be returned.
40

ERRORS

42       These functions may fail if:
43
44       Range Error
45              The  value  of  x  was  too  large in magnitude, or an underflow
46              occurred.
47
48       If the integer expression (math_errhandling & MATH_ERRNO) is  non-zero,
49       then  errno  shall  be  set  to  [ERANGE].  If  the  integer expression
50       (math_errhandling & MATH_ERREXCEPT) is  non-zero,  then  the  underflow
51       floating-point exception shall be raised.
52
53
54       No other errors shall occur.
55
56       The following sections are informative.
57

EXAMPLES

59       None.
60

APPLICATION USAGE

62       On   error,   the   expressions  (math_errhandling  &  MATH_ERRNO)  and
63       (math_errhandling & MATH_ERREXCEPT) are independent of each other,  but
64       at least one of them must be non-zero.
65

RATIONALE

67       None.
68

FUTURE DIRECTIONS

70       None.
71

SEE ALSO

73       feclearexcept(),  fetestexcept(),  isnan(),  y0(), the Base Definitions
74       volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Condi‐
75       tions for Mathematical Functions, <math.h>
76

78       Portions  of  this text are reprinted and reproduced in electronic form
79       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
80       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
81       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
82       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
83       event of any discrepancy between this version and the original IEEE and
84       The  Open Group Standard, the original IEEE and The Open Group Standard
85       is the referee document. The original Standard can be  obtained  online
86       at http://www.opengroup.org/unix/online.html .
87
88
89
90IEEE/The Open Group                  2003                               J0(3P)
Impressum