HP-UX Reference (11i v3 07/02) - 3 Library Functions N-Z (vol 7)

t
tgamma(3M) tgamma(3M)
(HP Integrity Server Only)
NAME
tgamma(), tgammaf(), tgammal(), tgammaw(), tgammaq() - true gamma functions
SYNOPSIS
#include <math.h>
double tgamma(double x);
float tgammaf(float x);
long double tgammal(long double x);
extended tgammaw(extended x);
quad tgammaq(quad x);
DESCRIPTION
The tgamma() function computes the true gamma function of x.
In contrast, the
lgamma(), lgamma_r() , and
gamma() functions compute the log of gamma.
tgammaf() is a float version of tgamma(); it takes a float argument and returns a float
result.
tgammal() is a long double version of tgamma(); it takes a long double argument and
returns a
long double result.
tgammaw() is an extended version of tgamma(); it takes an extended argument and returns an
extended result.
tgammaq() is equivalent to tgammal() on HP-UX systems.
USAGE
To use these functions compile either with the default -Ae option or with the -Aa
and
-D_HPUX_SOURCE options.
To use
tgammaw() or tgammaq() , compile also with the -fpwidetypes option.
To use any of these functions, make sure your program includes <math.h>, and link in the math library
by specifying -lm on the compiler or linker command line.
For more information, see the HP-UX floating-point guide for HP Integrity servers at the following site:
http://www.hp.com/go/fp
.
RETURN VALUE
If x equals ±0,
tgamma() returns ±INFINITY, and raises the divide-by-zero exception.
If x is a negative integer, tgamma() returns a NaN and raises the invalid exception.
If x equals -INFINITY, tgamma() returns a NaN and raises the invalid exception.
If x equals +INFINITY,
tgamma() returns +INFINITY.
If x is NaN,
tgamma() returns NaN.
tgamma() returns infinity (equal to HUGE_VAL) in lieu of a value whose magnitude is too large, and
raises the overflow and inexact exceptions.
tgamma() raises the inexact exception whenever a rounded result does not equal the mathematical
result.
ERRORS
If x is a negative integer, tgamma() sets errno to [EDOM].
HP-UX libm functions on Integrity servers do not set errno by default. For errno setting, compile
with the +Olibmerrno option.
SEE ALSO
exp(3M), lgamma(3M), log(3M), math(5).
STANDARDS CONFORMANCE
tgamma(), tgammaf(), tgammal() : ISO/IEC C99 (including Annex F, ‘‘IEC 60559 floating-point
arithmetic’’)
HP-UX 11i Version 3: February 2007 − 1 − Hewlett-Packard Company 569