GAMMA(3M)                                               GAMMA(3M)



     NAME
          gamma - log gamma function

     SYNOPSIS
          #include <math.h>

          double gamma(x)
          double x;

     DESCRIPTION
          gamma returns ln|Γ(x)|.

          The external integer signgam returns the sign of Γ(x) .

     IDIOSYNCRASIES
          Do not use the expression signgam*exp(gamma(x)) to compute g
          := Γ(x).  Instead use a program like this (in C):
               lg = gamma(x); g = signgam*exp(lg);

          Only after gamma has returned can signgam be correct.  Note
          too that Γ(x) must overflow when x is large enough,
          underflow when -x is large enough, and spawn a division by
          zero when x is a nonpositive integer.

     SEE ALSO
          math(3M)

     ORIGIN
          4.3 BSD


























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