j1(), j1f()

Compute a Bessel function of the first kind of order 1

Synopsis:

#include <math.h>

double j1( double x );

float j1f( float x );

libm: The general-purpose math library.
libm-sve: (QNX Neutrino 7.1 or later) 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.

These functions compute the Bessel function for x of the first kind of order 1.

To check for error situations, use feclearexcept() and fetestexcept(). For example:

Call feclearexcept(FE_ALL_EXCEPT) before calling j1() or j1f().
On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

The Bessel value of x of the first kind of order 1.

If:	These functions return:	Errors:
`x` is ±0.0	0.0, with the same sign as `x`	—
`x` is ±Inf	0.0, with the same sign as `x`	—
`x` is NaN	NaNNaN	—
The correct result would cause underflow	0.0	FE_UNDERFLOW

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.