gamma(3) [osf1 man page]

lgamma(3)						     Library Functions Manual							 lgamma(3)

NAME

       lgamma, gamma - Compute the logarithm of the gamma function

LIBRARY

       Math Library (libm.a)

SYNOPSIS

       #include <math.h>

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

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       lgamma():  XPG4

       gamma():  XPG4

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

DESCRIPTION

       The  lgamma(),  lgammaf(),  and lgammal() functions return the logarithm of the absolute value of gamma of x, or ln(|G(x)|), where G is the
       gamma function. The sign of gamma of x is returned in the external integer variable signgam.  The x parameter cannot be	0  or  a  negative
       integer.

       The gamma() function returns the natural log of the gamma function and so is functionally equivalent to lgamma().  Because of this, gamma()
       is marked TO BE WITHDRAWN in the X/Open Portability Guide, Revision 4 (XPG4).

       The following table describes function behavior in response to exceptional arguments:

       -------------------------------------------------------------------------
       Function 		       Exceptional Argument    Routine Behavior
       -------------------------------------------------------------------------
       lgamma(), lgammaf(), lgamma()   |x| = infinity	       Invalid argument
       lgamma(), lgammaf(), lgamma()   x = 0, -1, -2, -3,...   Invalid argument
       lgamma(), lgammaf(), lgamma()   x > lgamma_max_float    Overflow
       -------------------------------------------------------------------------

       The following table lists boundary values used by these functions:

       -------------------------------------------------------------------------
       Value		  Data	     Hexadecimal Value	 Decimal Value
       Name		  Type
       -------------------------------------------------------------------------
       lgamma_max_float   S_FLOAT    7BC650F9		 2.0594342e36
			  T_FLOAT    7F475ABDC501F55F	 1.2812545499066958e305
       -------------------------------------------------------------------------
       delim off

																	 lgamma(3)

Check Out this Related Man Page

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

NAME

     lgamma, lgammaf, lgamma_r, lgammaf_r, gamma, gammaf, gamma_r, gammaf_r, tgamma, tgammaf -- log gamma function

LIBRARY

     Math Library (libm, -lm)

SYNOPSIS

     #include <math.h>

     extern int signgam;

     double
     lgamma(double x);

     float
     lgammaf(float x);

     double
     lgamma_r(double x, int *sign);

     float
     lgammaf_r(float x, int *sign);

     double
     gamma(double x);

     float
     gammaf(float x);

     double
     gamma_r(double x, int *sign);

     float
     gammaf_r(float x, int *sign);

     double
     tgamma(double x);

     float
     tgammaf(float x);

DESCRIPTION
		   _
     lgamma(x) returns ln|| (x)|.
						       _
     The external integer signgam returns the sign of | (x).
													       _
     lgamma_r() is a reentrant interface that performs identically to lgamma(), differing in that the sign of | (x) is stored in the location
     pointed to by the sign argument and signgam is not modified.
						    _
     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() has returned can signgam be correct.

RETURN VALUES

     lgamma() returns 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.  On the VAX, the reserved operator is returned, and errno
     is set to ERANGE.

SEE ALSO

     math(3)

HISTORY

     The lgamma function appeared in 4.3BSD.  The tgamma() function appeared in NetBSD 6.0.

BSD
								    May 4, 2012 							       BSD

Linux and UNIX Man Pages

gamma(3) [osf1 man page]

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