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J0(3) FreeBSD Library Functions Manual J0(3) NAME j0, j0f, j1, j1f, jn, jnf, y0, y0f, y1, y1f, yn, ynf - Bessel functions of first and second kind LIBRARY Math Library (libm, -lm) SYNOPSIS #include <math.h> double j0(double x); float j0f(float x); double j1(double x); float j1f(float x); double jn(int n, double x); float jnf(int n, float x); double y0(double x); float y0f(float x); double y1(double x); float y1f(float x); double yn(int n, double x); float ynf(int n, float x); DESCRIPTION The functions j0(), j0f(), j1(), and j1f() compute the Bessel function of the first kind of orders 0 and 1 for the real value x; the functions jn() and jnf() compute the Bessel function of the first kind of the integer order n for the real value x. The functions y0(), y0f(), y1(), and y1f() compute the linearly independent Bessel function of the second kind of orders 0 and 1 for the positive real value x; the functions yn() and ynf() compute the Bessel function of the second kind for the integer order n for the positive real value x. RETURN VALUES These routines return values of their respective Bessel functions. For large positive inputs, they may underflow and return +-0. The following applies to y0(), y0f(), y1(), y1f(), yn(), and ynf(). If x is negative, including -infinity, these routines will generate an invalid exception and return NaN. If x is +-0, these routines will generate a divide-by-zero exception and return -infinity. If x is a sufficiently small positive number, then y1(), y1f(), yn(), and ynf() will generate an overflow exception and return -infinity. SEE ALSO math(3) STANDARDS The j0(), j1(), jn(), y0(), y1(), and yn() functions conform to IEEE Std 1003.1-2001 ("POSIX.1"). The float versions are extensions. HISTORY This set of functions appeared in Version 7 AT&T UNIX. FreeBSD 14.1-RELEASE-p8 March 10, 2015 FreeBSD 14.1-RELEASE-p8