ADAS Subroutine r8giiiav

      function r8giiiav(u, gam2)

C-----------------------------------------------------------------------
C
C  **************** FORTRAN77 REAL*8 FUNCTION: R8GIIIAV ****************
C
C
C  PURPOSE: CALCULATES MAXWELLIAN AVERAGED FREE-FREE GAUNT FACTORS
C
C  INPUT
C      U=HV/KT  WHERE HV IS PHOTON ENERGY
C               AND KT IS ELECTRON TEMPERATURE (ENERGY UNITS)
C      GAM2=Z*Z*IH/KT  WHERE Z IS TARGET ION CHARGE
C               AND IH IS THE RYDBERG ENERGY
C  OUTPUT
C      GIIIAV=MAXWELLIAN AVERAGED FREE-FREE GAUNT FACTOR.
C
C
C  AUTHOR   : H P Summers
C  DATE     : 22-11-1984
C
C
C  VERSION  : 1.1
C  DATE     : 02-03-2005
C  MODIFIED : Martin O'Mullane
C                - First version in central ADAS.
C                - Make implicit none.
C
C  VERSION  : 1.2
C  DATE     : 15-03-2006
C  MODIFIED : Allan Whiteford
C                - Removed external giii statement
C
C  VERSION  : 1.3                          
C  DATE     : 10-04-2007
C  MODIFIED : Allan Whiteford
C               - Modified documentation as part of automated
C		  subroutine documentation preparation.
C
C-----------------------------------------------------------------------
C
C-----------------------------------------------------------------------
      REAL*8              GAM2,        U