Y0(3) Library Functions Manual Y0(3)

y0 y1 yn — Bessel functions of the second kind

#include <math.h>

double y0(double x);
double y1 (double x);
double yn (int n, double x);

The y0() , y1() and yn() functions compute Bessel functions of x of the second kind of orders 0, 1 and n respectively. The value of x must be positive.

An application wishing to check for error situations should set errno to 0 before calling y0(), y1() or yn(). If errno is non-zero on return, or the return value is NaN, an error has occurred.

Upon successful completion, y0() , y1() and yn() will return the relevant Bessel value of x of the second kind.

If x is NaN, NaN is returned and errno may be set to [EDOM].

If the x argument to y0(), y1() or yn() is negative, -HUGE_VAL or NaN is returned, and errno may be set to [EDOM].

If x is 0.0, -HUGE_VAL is returned and errno may be set to [ERANGE] or [EDOM].

If the correct result would cause underflow, 0.0 is returned and errno may be set to [ERANGE].

If the correct result would cause overflow, -HUGE_VAL or 0.0 is returned and errno may be set to [ERANGE].

The y0() , y1() and yn() functions may fail if:

The value of x is negative or NaN.
The value of x is too large in magnitude, or x is 0.0, or the correct result would cause overflow or underflow.

No other errors will occur.

None.

None.

None.

isnan(3) , j0(3) , <math.h> .

Derived from Issue 1 of the SVID.

February 1997 posix.fail