Section: POSIX Programmer's Manual (3P)
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
--- Bessel functions of the first kind
double j0(double x);
double j1(double x);
double jn(int n, double x);
functions shall compute Bessel functions of
of the first kind of orders 0, 1, and
An application wishing to check for error situations should set
to zero and call
before calling these functions. On return, if
is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO |
FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.
Upon successful completion, these functions shall return the relevant
Bessel value of
of the first kind.
argument is too large in magnitude, or the correct result would cause
underflow, 0 shall be returned and a range error may occur.
is NaN, a NaN shall be returned.
These functions may fail if:
- Range Error
The value of
was too large in magnitude, or an underflow occurred.
If the integer expression (math_errhandling & MATH_ERRNO) is
shall be set to
If the integer expression (math_errhandling & MATH_ERREXCEPT) is
non-zero, then the underflow floating-point exception shall be raised.
No other errors shall occur.
The following sections are informative.
On error, the expressions (math_errhandling
& MATH_ERRNO) and
& MATH_ERREXCEPT) are independent of each
other, but at least one of them must be non-zero.
The Base Definitions volume of POSIX.1-2017,
Section 4.20, Treatment of Error Conditions for Mathematical Functions,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
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