lgammaf

LGAMMA(3)		  Linux Programmer’s Manual		    LGAMMA(3)



NAME
       lgamma,	lgammaf,  lgammal, lgamma_r, lgammaf_r, lgammal_r - log gamma
       function

SYNOPSIS
       #include <math.h>

       double lgamma(double x);
       float lgammaf(float x);
       long double lgammal(long double x);

       double lgamma_r(double x, int *signp);
       float lgammaf_r(float x, int *signp);
       long double lgammal_r(long double x, int *signp);

DESCRIPTION
       For the definition of the Gamma function, see tgamma(3).

       The lgamma() function returns the natural logarithm  of	the  absolute
       value  of  the  Gamma  function.	  The  sign  of the Gamma function is
       returned in the external integer signgam declared in <math.h>.  It  is
       1 when the Gamma function is positive or zero, -1 when it is negative.

       Since using a constant location signgam is not thread-safe, the	func-
       tions  lgamma_r() etc. have been introduced; they return this sign via
       the parameter signp.

       For nonpositive integer values of x, lgamma() returns  HUGE_VAL,	 sets
       errno  to  ERANGE  and  raises the zero divide exception.  (Similarly,
       lgammaf() returns HUGE_VALF and lgammal() returns HUGE_VALL.)

ERRORS
       An application wishing to check for error situations should set	errno
       to  zero	 and  call  feclearexcept(FE_ALL_EXCEPT) before calling these
       functions. On return, if errno is non-zero or  fetestexcept(FE_INVALID
       | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
       occurred.

       A range error occurs if x is too large.	A pole error occurs if x is a
       negative integer or zero.

CONFORMING TO
       C99, SVID 3, BSD 4.3

SEE ALSO
       tgamma(3)



				  2002-08-10			    LGAMMA(3)