The
j0()
and
j1()
functions return Bessel functions of x
of the first kind of orders 0 and 1, respectively.
The
jn()
function
returns the Bessel function of x of the first kind of order n.

The
j0f()
etc. and
j0l()
etc. functions are versions that take and return
float
and
long double
values, respectively.

RETURN VALUE

On success, these functions return the appropriate
Bessel value of the first kind for
x.

If
x
is a NaN, a NaN is returned.

If
x
is too large in magnitude,
or the result underflows,
a range error occurs,
and the return value is 0.

ERRORS

See
math_error(7)
for information on how to determine whether an error has occurred
when calling these functions.

The following errors can occur:

Range error: result underflow, or x is too large in magnitude

errno
is set to
ERANGE.

These functions do not raise exceptions for
fetestexcept(3).

CONFORMING TO

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

BUGS

There are errors of up to 2e-16 in the values returned by
j0(),
j1()
and
jn()
for values of x between -8 and 8.

This page is part of release 3.27 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.