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lgamma(3)
NAME
  lgamma, gamma - Compute the logarithm of the gamma function

SYNOPSIS
  #include <math.h>

  double lgamma(
	  double x );

  float lgammaf(
	  float x );

  long double lgammal(
	  long double x );

LIBRARY
  Math Library (libm)

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  TO BE WITHDRAWN in the X/Open Portability Guide, Revision 4 (XPG4).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
  ___________________________________________________________________________
				   |x| = infinity	     Invalid argument

  lgamma(), lgammaf(), lgamma()
				   x = 0, -1, -2, -3,...     Invalid argument

  lgamma(), lgammaf(), lgamma()

							     Overflow

  lgamma(), lgammaf(), lgamma()

				   x > lgamma_max_float
  ___________________________________________________________________________

  The following table lists boundary values used by these functions:

  _________________________________________________________________________
  Value Name	     Data Type	 Hexadecimal Value   Decimal Value
  _________________________________________________________________________
  lgamma_max_float   S_FLOAT	 7BC650F9	     2.0594342e36
		     T_FLOAT	 7F475ABDC501F55F

						     1.2812545499066958e305
  _________________________________________________________________________

Index for Section 3

Alphabetical listing for L

Top of page