ADAS Subroutine ingamq

      function ingamq(a,x)
	
C-----------------------------------------------------------------------
C
C    ****************** fortran77 function: ingamq ****************** 
C
C  purpose: evaluates incomplete gamma function, 1-P(a,x)
C
C  calling program: various
C
C  input : (r*8)  x      = function argument
C  input : (r*8)  a      = function argument
C
C  output: (r*8)  ingamq = function name
C
C  author: Paul Bryans, University of Strathclyde
C
C  date:   20/02/04
C
C  update: 
C
C-----------------------------------------------------------------------
      REAL*8              A,           X