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LGAMMA(3)	       FreeBSD Library Functions Manual		     LGAMMA(3)

NAME
     lgamma, lgamma_r, lgammaf,	lgammaf_r, lgammal, lgammal_r, gamma, gamma_r,
     gammaf, gammaf_r, tgamma, tgammaf,	tgammal, -- 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);

     long double
     tgammal(long double 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), tgammaf(x),	and tgammal(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
     D_	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	argu-
     ments it is accurate to within one	unit in	the last place.	 Exponentia-
     tion 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.

BUGS
     To	conform	with newer C/C++ standards, a stub implementation for tgammal
     was committed to the math library,	where tgammal is mapped	to tgamma.
     Thus, the numerical accuracy is at	most that of the 53-bit	double preci-
     sion implementation.

SEE ALSO
     math(3)

STANDARDS
     The lgamma(), lgammaf(), lgammal(), tgamma(), tgammaf(), and tgammal()
     functions are expected to conform to ISO/IEC 9899:1999 (``ISO C99'').

HISTORY
     The lgamma() function appeared in 4.3BSD_	The gamma() function appeared
     in	4.4BSD as a function which computed | (x).  This version was used in
     FreeBSD 1.1.  The name gamma() was	originally dedicated to	the lgamma()
     function, and that	usage was restored by switching	to Sun's fdlibm	in
     FreeBSD 1.1.5.  The tgamma() function appeared in FreeBSD 5.0.

FreeBSD	11.2		       December	8, 2017			  FreeBSD 11.2

NAME | LIBRARY | SYNOPSIS | IDIOSYNCRASIES | RETURN VALUES | BUGS | SEE ALSO | STANDARDS | HISTORY

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