c
c $Id: isdigit.f,v 1.1 1999/08/03 21:21:32 aai Exp $.
c
c{
      logical function isdigit(s)
      character*1 s
c
c     Islpha: Return .TRUE. if a character is a letter.
c             Return .FALSE. otherwise.
c
c     This routine must be declared LOGICAL by the caller.
c
c     Phillip A. Cheeseman, Purdue University Computing Center.
c
      character*10 digits
c
      data digits /'0123456789'/
c
      isdigit = index(digits,s).ne.0
c
      return
c
      end
c}