Compute the gamma function of a number
#include <math.h> double tgamma( double x ); float tgammaf( float x ); long double tgammal( long double x );
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:
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.
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | No |
Thread | Yes |