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J0(3) Linux Programmer's Manual J0(3)

NAME

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

SYNOPSIS

     #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():
         _XOPEN_SOURCE
             || /* Since glibc 2.19: */ _DEFAULT_SOURCE
             || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
     j0f(), j0l(), j1f(), j1l(), jnf(), jnl():
         _XOPEN_SOURCE  >= 600
             || (_ISOC99_SOURCE && _XOPEN_SOURCE)
             || /* Since glibc 2.19: */ _DEFAULT_SOURCE
             || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE

DESCRIPTION

     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(), j1f(), and jnf(),  functions  are  versions  that  take  and
     return  float  values.   The j0l(), j1l(), and jnl() functions are ver-
     sions that take and return long double values.

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).

ATTRIBUTES

     For   an   explanation   of   the  terms  used  in  this  section,  see
     attributes(7).

     +-------------------+---------------+---------+
     |Interface          | Attribute     | Value   |
     +-------------------+---------------+---------+
     |j0(), j0f(), j0l() | Thread safety | MT-Safe |
     +-------------------+---------------+---------+
     |j1(), j1f(), j1l() | Thread safety | MT-Safe |
     +-------------------+---------------+---------+
     |jn(), jnf(), jnl() | Thread safety | MT-Safe |
     +-------------------+---------------+---------+

CONFORMING TO

     The functions returning double conform to SVr4,  4.3BSD,  POSIX.1-2001,
     and POSIX.1-2008.  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.