c       ************************************************************************
c       *
c       *   sysfun.f -
c       *
c       *   Copyright (c) 1995
c       *
c       *   ETH Zuerich
c       *   Institut fuer Molekularbiologie und Biophysik
c       *   ETH-Hoenggerberg
c       *   CH-8093 Zuerich
c       *
c       *   All Rights Reserved
c       *
c       *   Date of last modification : 95/09/15
c       *   Pathname of SCCS file     : /export/home3/cb/garant-1.0/src/SCCS/s.sysfun.f
c       *   SCCS identification       : 1.3
c       *
c       ************************************************************************
c     ==================================================================
c     SYSFUN: Evaluate external (non-Fortran) functions.
c
c             Peter G"untert, 12-08-1994
c     ------------------------------------------------------------------
      subroutine sysfun (func,iarg,narg,inum,rnum,cnum,snum,numtyp)
c
      character*(*) func,snum(*)
      dimension iarg(*),inum(*),rnum(*),numtyp(*)
      complex cnum(*),c
c
      i1=iarg(1)
c     -------------------------------------- functions without arguments
      if (narg.eq.0) then
        numtyp(i1)=1
        if (func.eq.'pi') then
          rnum(i1)=3.141592654
          numtyp(i1)=2
        else
          go to 900
        end if
c     ---------------------- functions with variable number of arguments
c      else if (func.eq.'sval') then
c     -------------------------------------- functions with one argument
      else if (narg.eq.1) then
c       ............................ functions with one integer argument
        if (numtyp(i1).eq.1) then
          i=inum(i1)
          if (func.eq.'idummy') then
            inum(i1)=2*i
          else
            rnum(i1)=i
            numtyp(i1)=2
            go to 200
          end if
          go to 800
        end if
c       ............................... functions with one real argument
  200   if (numtyp(i1).eq.2) then
          r=rnum(i1)
          if (func.eq.'rdummy') then
            rnum(i1)=2.0*r
          else
            cnum(i1)=c
            numtyp(i1)=3
            go to 300
          end if
          go to 800
        end if
c       ............................ functions with one complex argument
  300   if (numtyp(i1).eq.3) then
          c=cnum(i1)
          if (func.eq.'cdummy') then
            cnum(i1)=2.0*c
          else
            go to 900
          end if
          go to 800
c       .......................... functions with one character argument
        else if (numtyp(i1).eq.4) then
          if (func.eq.'sdummy') then
            numtyp(i1)=1
          else
            go to 900
          end if
          go to 800
        end if
        go to 900
c     -------------------------------------------------- other functions
      else
        go to 900
      end if
  800 return
c     ------------------------------------------------------------ error
  900 numtyp(i1)=0
      end