      subroutine ac_int(nt,acor,acint) ! bernd berg, feb 14 2001.
c input:  array of autocorrelations acor.
c output: array of integrated autocorrelation times acint.
      include '../../libs/fortran/implicit.sta'
      include '../../libs/fortran/constants.par'
      dimension acor(0:nt),acint(0:nt)
      acint(0)=one
      do it=1,nt
        acint(it)=acint(it-1)+two*acor(it)/acor(0)
      end do
      return
      end
