subroutine DFT(nmax,mmax,g,gf)
      integer nmax, mmax
      real g(0:nmax)
      complex gf(-mmax/2:mmax/2)
      complex W, i
      real pi

      pi=3.14159
      i=(0.0,1.0)
      W=exp(-2.0*i*pi/(nmax+1))
      do 10 j=-mmax/2,mmax/2
         gf(j)=g(0)
         do 20 k=1,nmax
            gf(j)=gf(j)+g(k)*(W**(j*k))
  20  continue
         gf(j)=gf(j)/(real(nmax+1))
  10  continue
      return
      end