TGAMMA(3) BSD Library Functions Manual TGAMMA(3)NAME
tgamma, lgamma, gamma — gamma and log of gammaSYNOPSIS
#include <math.h>
double
tgamma(double x);
float
tgamma(float x);
double
lgamma(double x);
float
lgamma(float x);
double
gamma(double x);
DESCRIPTIONtgamma() 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 ALSOmath(3)STANDARDS
The tgamma() , tgammf() , lgamma() , and lgammaf() functions conform to
ISO/IEC 9899:1999(E).
July 23, 2003