c **********************************************************************
      function f3(x)
c **********************************************************************
c
c     function f3(x)=-log(x)
c
c     0 < x <1.0d-32 it returns -log(1.0d-32)
c     x < 0          it returns 0
c
c **********************************************************************
      implicit real*8 (a-h,o-z)
c
      eps=1.0d-32
      if(x.lt.0) then
         f3=0.0d0
      else if(x.lt.eps) then
         f3=-log(eps)
      else
         f3=-log(x)
      endif
c
      end