1J0(P) POSIX Programmer's Manual J0(P)
2
3
4
6 j0, j1, jn - Bessel functions of the first kind
7
9 #include <math.h>
10
11 double j0(double x);
12 double j1(double x);
13 double jn(int n, double x);
14
15
17 The j0(), j1(), and jn() functions shall compute Bessel functions of x
18 of the first kind of orders 0, 1, and n, respectively.
19
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.
25
27 Upon successful completion, these functions shall return the relevant
28 Bessel value of x of the first kind.
29
30 If the x argument is too large in magnitude, or the correct result
31 would cause underflow, 0 shall be returned and a range error may occur.
32
33 If x is NaN, a NaN shall be returned.
34
36 These functions may fail if:
37
38 Range Error
39 The value of x was too large in magnitude, or an underflow
40 occurred.
41
42 If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
43 then errno shall be set to [ERANGE]. If the integer expression
44 (math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow
45 floating-point exception shall be raised.
46
47
48 No other errors shall occur.
49
50 The following sections are informative.
51
53 None.
54
56 On error, the expressions (math_errhandling & MATH_ERRNO) and
57 (math_errhandling & MATH_ERREXCEPT) are independent of each other, but
58 at least one of them must be non-zero.
59
61 None.
62
64 None.
65
67 feclearexcept() , fetestexcept() , isnan() , y0() , the Base Definiā
68 tions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error
69 Conditions for Mathematical Functions, <math.h>
70
72 Portions of this text are reprinted and reproduced in electronic form
73 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
74 -- Portable Operating System Interface (POSIX), The Open Group Base
75 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
76 Electrical and Electronics Engineers, Inc and The Open Group. In the
77 event of any discrepancy between this version and the original IEEE and
78 The Open Group Standard, the original IEEE and The Open Group Standard
79 is the referee document. The original Standard can be obtained online
80 at http://www.opengroup.org/unix/online.html .
81
82
83
84IEEE/The Open Group 2003 J0(P)