ond kind SYNOPSIS #include <math.h> double y0(double x); double y1(double x); double yn(int n, double x); float y0f(float x); float y1f(float x); float ynf(int n, float x); long double y0l(long double x); long double y1l(long double x); long double ynl(int n, long double x); Link with -lm. Feature Test Macro Requirements for glibc (seefeature_test_macros(7)): y0(), y1(), yn(): _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE y0f(), y0l(), y1f(), y1l(), ynf(), ynl(): _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 600 DESCRIPTION The y0() and y1() functions return Bessel functions of x of the second kind of orders 0 and 1, respectively. The yn() function returns the Bessel function of x of the second kind of order n. The value of x must be positive. The y0f() etc. and y0l() 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 second kind for x. If x is a NaN, a NaN is returned. If x is negative, a domain error occurs, and the functions return -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively. (POSIX.1-2001 also allows a NaN return for this case.) If x is 0.0, a pole error occurs, and the functions return -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively. If the result underflows, a range error occurs, and the functions return 0.0 If the result overflows, a range error occurs, and the functions return -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively. (POSIX.1-2001 also Pole error: x is 0.0 errno is set to ERANGE (but see BUGS). No FE_DIVBYZERO excep- tion is returned byfetestexcept(3)for this case. Range error: result underflow errno is set to ERANGE. No FE_UNDERFLOW exception is returned byfetestexcept(3)for this case. Range error: result overflow errno is not set for this case. An overflow floating-point exception (FE_OVERFLOW) is raised. 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 On a pole error, these functions set errno to EDOM, instead of ERANGE as POSIX.1-2004 requires. In glibc version 2.3.2 and earlier, these functions do not raise an invalid floating-point exception (FE_INVALID) when a domain error occurs. SEE ALSOj0(3)COLOPHON This page is part of release 3.54 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/. 2008-08-10Y0(3)