1J0(3P) POSIX Programmer's Manual J0(3P)
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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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12 j0, j1, jn — Bessel functions of the first kind
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15 #include <math.h>
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17 double j0(double x);
18 double j1(double x);
19 double jn(int n, double x);
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22 The j0(), j1(), and jn() functions shall compute Bessel functions of x
23 of the first kind of orders 0, 1, and n, respectively.
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25 An application wishing to check for error situations should set errno
26 to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
27 functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
28 FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
29 occurred.
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32 Upon successful completion, these functions shall return the relevant
33 Bessel value of x of the first kind.
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35 If the x argument is too large in magnitude, or the correct result
36 would cause underflow, 0 shall be returned and a range error may occur.
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38 If x is NaN, a NaN shall be returned.
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41 These functions may fail if:
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43 Range Error The value of x was too large in magnitude, or an underflow
44 occurred.
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46 If the integer expression (math_errhandling & MATH_ERRNO)
47 is non-zero, then errno shall be set to [ERANGE]. If the
48 integer expression (math_errhandling & MATH_ERREXCEPT) is
49 non-zero, then the underflow floating-point exception shall
50 be raised.
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52 No other errors shall occur.
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54 The following sections are informative.
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57 None.
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60 On error, the expressions (math_errhandling & MATH_ERRNO) and
61 (math_errhandling & MATH_ERREXCEPT) are independent of each other, but
62 at least one of them must be non-zero.
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65 None.
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68 None.
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71 feclearexcept(), fetestexcept(), isnan(), y0()
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73 The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of
74 Error Conditions for Mathematical Functions, <math.h>
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77 Portions of this text are reprinted and reproduced in electronic form
78 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
79 table Operating System Interface (POSIX), The Open Group Base Specifi‐
80 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
81 Electrical and Electronics Engineers, Inc and The Open Group. In the
82 event of any discrepancy between this version and the original IEEE and
83 The Open Group Standard, the original IEEE and The Open Group Standard
84 is the referee document. The original Standard can be obtained online
85 at http://www.opengroup.org/unix/online.html .
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87 Any typographical or formatting errors that appear in this page are
88 most likely to have been introduced during the conversion of the source
89 files to man page format. To report such errors, see https://www.ker‐
90 nel.org/doc/man-pages/reporting_bugs.html .
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94IEEE/The Open Group 2017 J0(3P)