TGAMMA(3) | Linux Programmer's Manual | TGAMMA(3) |
NAME
tgamma, tgammaf, tgammal - true gamma functionSYNOPSIS
#include <math.h>Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or
cc -std=c99
DESCRIPTION
The Gamma function is defined byGamma(x) = integral from 0 to infinity of t^(x-1) e^-t dt
Gamma(m+1) = m!
Gamma(x+1) = x * Gamma(x)
Gamma(x) * Gamma(1 - x) = PI / sin(PI * x)
RETURN VALUE
On success, these functions return Gamma(x).ERRORS
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.The following errors can occur:
- Domain error: x is a negative integer, or negative infinity
- errno is set to EDOM. An invalid floating-point exception ( FE_INVALID) is raised (but see BUGS).
- Pole error: x is +0 or -0
- errno is set to ERANGE. A divide-by-zero floating-point exception ( FE_DIVBYZERO) is raised.
- Range error: result overflow
- errno is set to ERANGE. An overflow floating-point exception ( FE_OVERFLOW) is raised.
glibc also gives the following error which is not specified in C99 or POSIX.1-2001.
- Range error: result underflow
- An underflow floating-point exception ( FE_UNDERFLOW) is raised.
- errno is not set for this case.
VERSIONS
These functions first appeared in glibc in version 2.1.CONFORMING TO
C99, POSIX.1-2001.NOTES
This function had to be called "true gamma function" since there is already a function gamma(3) that returns something else (see gamma(3) for details).BUGS
If x is negative infinity, errno is not set (it should be set to EDOM).SEE ALSO
gamma(3), lgamma(3)COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.2010-09-20 | GNU |