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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).

     allbox; lb lb lb l l  l.   Interface Attribute Value  T{  j0(),  j0f(),
     j0l()  T}   Thread  safety  MT-Safe  T{  j1(), j1f(), j1l() T}   Thread
     safety  MT-Safe T{ jn(), jnf(), jnl() T}   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.