## Linux and UNIX Man Pages

Test Your Knowledge in Computers #740
Difficulty: Medium
FORTRAN II first appeared in 1958.
True or False?

# lgammaf(3) [freebsd man page]

```LGAMMA(3)						   BSD Library Functions Manual 						 LGAMMA(3)

NAME
lgamma, lgamma_r, lgammaf, lgammaf_r, lgammal, lgammal_r, gamma, gamma_r, gammaf, gammaf_r, tgamma, tgammaf -- log gamma functions, gamma
function

LIBRARY
Math Library (libm, -lm)

SYNOPSIS
#include <math.h>

extern int signgam;

double
lgamma(double x);

double
lgamma_r(double x, int *signgamp);

float
lgammaf(float x);

float
lgammaf_r(float x, int *signgamp);

long double
lgammal(long double x);

long double
lgammal_r(long double x, int *signgamp);

double
gamma(double x);

double
gamma_r(double x, int *signgamp);

float
gammaf(float x);

float
gammaf_r(float x, int *signgamp);

long double
tgamma(double x);

float
tgammaf(float x);

DESCRIPTION					      _ 							_
lgamma(x), lgammaf(x), and lgammal(x) return ln|| (x)|.  The external integer signgam returns the sign of | (x).

lgamma_r(x, signgamp), lgammaf_r(x, signgamp), and lgammal_r(x, signgamp)_provide the same functionality as lgamma(x), lgammaf(x), and
lgammal(x), but the caller must provide an integer to store the sign of | (x).
_
The tgamma(x) and tgammaf(x) functions return | (x), with no effect on signgam.

gamma(), gammaf(), gamma_r(), and gammaf_r() are deprecated aliases for lgamma(), lgammaf(), lgamma_r(), and lgammaf_r(), respectively.

IDIOSYNCRASIES								   _
Do not use the expression ``signgam*exp(lgamma(x))'' to compute g := | (x).  Instead use a program like this (in C):

lg = lgamma(x); g = signgam*exp(lg);

Only after lgamma() or lgammaf() has returned can signgam be correct.

For arguments in its range, tgamma() is preferred, as for positive arguments it is accurate to within one unit in the last place.	Exponenti-
ation of lgamma() will lose up to 10 significant bits.

RETURN VALUES
gamma(), gammaf(), gammal(), gamma_r(), gammaf_r(), gammal_r(), lgamma(), lgammaf(), lgammal(), lgamma_r(), lgammaf_r(), and lgammal_r()
return appropriate values unless an argument is out of range.  Overflow will occur for sufficiently large positive values, and non-positive
integers.	For large non-integer negative values, tgamma() will underflow.