ADAS Subroutine r8erfc

       function r8erfc( x )
c-----------------------------------------------------------------------
c
c  ****************** fortran77 function: r8erfc *********************
c
c  purpose:  calculates the error function erfc(x)   
c
c  calling program: various
c
c
c
c  input : (i*4)  x      = independent variable.
c  output: (r*8)  r8erfc = erfc(x).
c
c  routines:
c          none
c
c  author:  Hugh Summers, University of Strathclyde
c           JA7.08
c           tel. 0141-548-4196
c
c  date:    15/01/02
c
c  update:
c
c-----------------------------------------------------------------------
      REAL*8              X