opendarwin man page for gamma

TGAMMA(3)						   BSD Library Functions Manual 						 TGAMMA(3)

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

SYNOPSIS
     #include <math.h>

     double
     tgamma(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() , tgammf() , lgamma() , and lgammaf() functions conform to ISO/IEC 9899:1999(E).

								   July 23, 2003