ADAS Subroutine ngffmh

       REAL*8 FUNCTION NGFFMH(GAM2)
       IMPLICIT REAL*8(A-H,O-Z)
C-----------------------------------------------------------------------
C
C  ************** FORTRAN77 SUBROUTINE: NGFFMH  ************************
C
C  VERSION:  1.0
C
C  PURPOSE: EVALUATES ELECTRON TEMPERATURE AND FREQUENCY AVERAGED
C           HYDROGENIC FREE FREE GAUNT FACTOR.
C
C  OBTAINED FROM INTERPOLATION OF KARZAS & LATTER (1959) FIG.6
C  FOR -3<LOG10(Z0*Z0*IH/KTE)<1. OUTSIDE THIS RANGE A VERY APPROXIMATE
C  EXTRAPOLATION IS PERFORMED WITH GFFMH=1 IN THE INFINITE LIMITS.
C
C  INPUT:
C       GAM2=Z0*Z0*IH/KTE
C  OUTPUT:
C       NGFFMH=MAXWELL AND FREQUENCY AVERAGED FREE-FREE GAUNT FACTOR.
C  ********* H.P.SUMMERS, JET         12 JAN 1987    ******************
C-----------------------------------------------------------------------
C
C UNIX-IDL CONVERSION:
C
C VERSION: 1.1                          DATE: 22-08-96
C MODIFIED: WILLIAM OSBORN
C               - FIRST CONVERTED. NO CHANGES.
C
C VERSION: 1.2                          DATE: 13-09-99
C MODIFIED: Martin O'Mullane
C               - Define function name as real*8.
C
C VERSION: 1.3                          DATE: 16-05-07
C MODIFIED: Martin O'Mullane
C               - Modified comments as part of subroutine documentation
C                 procedure.
C
C-----------------------------------------------------------------------
      REAL*8              GAM2