yn(), ynf()
QNX SDP8.0C Library ReferenceAPIDeveloper
Compute a Bessel function of the second kind of a given order
Synopsis:
#include <math.h>
double yn( int n,
double x );
float ynf( int n,
float x );
Arguments:
- n, x
- The numbers that you want to compute the Bessel function for.
Library:
- libm
- The general-purpose math library.
- libm-sve
- A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.
Your system requirements will determine how you should work with these libraries:
- If you want only selected processes to run with the SVE version, you can include both libraries in your OS image and use the -l m or -l m-sve option to qcc to link explicitly against the appropriate one.
- If you want all processes to use the SVE version, include libm-sve.so in your OS image and set up a symbolic link from libm.so to libm-sve.so. Use the -l m option to qcc to link against the library.
Note:
Compile your program with the -fno-builtin option to prevent the compiler from using a
built-in version of the function.
Description:
These functions compute the Bessel function for x of the second kind of order n.
To check for error situations, use feclearexcept() and fetestexcept(). For example:
- Call
feclearexcept(FE_ALL_EXCEPT)before calling yn() or ynf(). - On return, if
fetestexcept(FE_ALL_EXCEPT)is nonzero, then an error has occurred.
Returns:
The result of the Bessel function for x of the second kind of order n.
| If x is: | These functions return: | Errors: |
|---|---|---|
| Negative, including -Inf | NaN | FE_INVALID |
| ±0.0 | -Inf | FE_DIVBYZERO |
| NaN | NaN | — |
| Inf | 0.0 | — |
| If the correct result would cause: | These functions return: | Errors: |
|---|---|---|
| Overflow | -Inf | FE_OVERFLOW |
| Underflow | 0.0 |
These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.
Classification:
yn() is POSIX 1003.1 XSI; ynf() is Unix
| Safety: | |
|---|---|
| Cancellation point | No |
| Signal handler | Yes |
| Thread | Yes |
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