NAME    [Toc]    [Back]

     lgamma, lgammaf - log gamma functions

SYNOPSIS    [Toc]    [Back]

     #include <math.h>

     extern int signgam;

     double
     lgamma(double x);

     float
     lgammaf(float x);

DESCRIPTION                _
     lgamma(x) returns ln|| (x)|.
                                                       _
     The external integer signgam returns the sign of | (x).  The
lgammaf()
     function is a single precision version of lgamma().

IDIOSYNCRASIES    [Toc]    [Back]

_
     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    [Toc]    [Back]

     lgamma()  returns  appropriate  values unless an argument is
out of range.
     Overflow will occur for sufficiently large positive  values,
and non-positive
  integers.   On  the  VAX, the reserved operator is returned, and errno
     is set to ERANGE.

SEE ALSO    [Toc]    [Back]

     infnan(3), math(3)

HISTORY    [Toc]    [Back]

     The lgamma() function appeared in 4.3BSD.

OpenBSD     3.6                        December      3,      1992