TGAMMA(3)

NAME
tgamma, lgamma, gamma - gamma and log of gamma

SYNOPSIS
#include <math.h>
double
tgamma(double x);
long double
tgammal(long double x);
float
tgamma(float x);
double
lgamma(double x);
float
lgamma(float x);
double
gamma(double x);

DESCRIPTION
tgamma() calculates the gamma function of x. lgamma() calculates the natural logorithm of the absolute value of the gamma function of x. gamma() is the same function as tgamma. Its use is deprecated.

SPECIAL VALUES
tgamma(±0) returns ±infinity and raises the "divide-by-zero" floating-point exception.

tgamma(x) returns a NaN and raises the "invalid" floating-point exception if x is a negative integer.

tgamma(-infinity) returns a NaN and raises the "invalid" floating-point exception.

tgamma(+infinity) returns +infinity.

tgamma(x) generates a domain error if x is a negative integer or if the result cannnot be respresented when x is 0.

A range error may occur if the magnitude of x is too large or too small.

gamma() has the same behavior as tgamma()

lgamma(1) returns +0.

lgamma(2) returns +0.

lgamma(x) returns +infinity and raises the "divide-by-zero" floating-point exception if x is a negative integer or 0.

lgamma(±infinity) returns +infinity.

lgamma(x) generates a range error if x is too large.

A range error may occur if x is a negative integer or 0.

SEE ALSO
math(3)

STANDARDS
The tgamma() , and lgamma() functions conform to ISO/IEC 9899:1999(E).