tgamma(), tgammaf(), tgammal()

Synopsis:

#include <math.h>

double tgamma( double x );

float tgammaf( float x );

long double tgammal( long double 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.

The tgamma(), tgammaf(), and tgammal() functions compute Γ(x), which is defined as follows:

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

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

The gamma of x.

If `x` is:	These functions return:	Errors:
A negative integer	NaN	FE_INVALID
±0.0	Inf, with the same sign as `x`	FE_DIVBYZERO
A value that would cause overflow	±Inf, with the same sign as the correct value	FE_OVERFLOW
A value that would cause underflow	0.0	FE_UNDERFLOW
Subnormal and 1 / `x` is representable	1 / `x`	—
NaN	NaN	—
Inf	Inf	FE_OVERFLOW
-Inf	NaN	FE_INVALID

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