tgamma(), tgammaf(), tgammal()

Updated: May 06, 2022

Compute the gamma function of a number

Synopsis:

#include <math.h>

double tgamma( double x );

float tgammaf( float x );

long double tgammal( long double x );

Arguments:

x
An arbitrary number.

Library:

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:

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.

Description:

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:

Returns:

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.

Classification:

C11, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes