c=======================================================================

      subroutine usersat(srr,wmin,wmax,dww,nnf) 1
      dimension srr(*)

c
c     user specified filter function
c
      open(unit=13,file='filter.dat',status='old',form='formatted')
      read(13,*) wmin,wmax,dww,nnf,(srr(i),i=1,nnf)
      close(unit=13)
c
      return
      end