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English pages are provided only to compare translations to original pages, better looking pages can be browsed at the Linux man-pages official site.
#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 (see feature_test_macros(7)):
y0(), y1(), yn():
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(), y1f(), and ynf() functions are versions that take and return float values. The y0l(), y1l(), and ynl() functions are versions that take and return long double values.
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 allows a 0.0 return for this case.)
The following errors can occur:
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.