ADAS Subroutine a8gser

       subroutine a8gser( gamser, a    , x    , gln )
c---------------------------------------------------------------------
c
c  ********************* fortran77 function a8gser *******************
c
c  purpose: to evaluate the series expansion for the incomplete gamma 
c           function p(a,x) - based on numerical recipes  
c
c  calling program:  a8gamp.for
c
c  input:
c            (r*8)  a      = parameter of p(a,x)
c            (r*8)  x      = paramete of p(a,x)
c  output:
c            (r*8)  gamser = incomplete gamma function gamma(a,x)
c                            (n.b. for x<0 takes principal value of 
c                             logarithm)
c            (r*8)  gln    = ln(gamma(a))
c
c
c  routines: 
c             none
c             a8gaml    adas    obtains log(gamma(a))
c
c  author:   Hugh Summers, University of Strathclyde ext.4196
c
c
c  version 1.1                             date:     25/06/99
c  modified: Hugh Summers
c		- first release
c
c-----------------------------------------------------------------------
      REAL*8              A,           GAMSER,      GLN,         X