subroutine fderiv(x,i,a,deltaa,nterms,deriv)
      implicit double precision (a-h,o-z)
      dimension x(100),a(10),deltaa(10),deriv(10)
      xi=x(i)
      factor=1.
      do 100 i=1,6
      deriv(i)=factor
100   factor=factor*xi
      return
      end