j0, j0f, j0l, j1, j1f, j1l, jn, jnf, jnl - Bessel functions of the first kind


#include <math.h>

double j0(double x); double j1(double x); double jn(int n, double x);

float j0f(float x); float j1f(float x); float jnf(int n, float x);

long double j0l(long double x); long double j1l(long double x); long double jnl(int n, long double x);

Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

j0(), j1(), jn(): _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE j0f(), j0l(), j1f(), j1l(), jnf(), jnl(): _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 600


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.


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.


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).


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


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 3.23 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at

openSUSE Logo