subroutine zfftb(n,c,Wsave)
use fftpack_kind
implicit none
real(rk) :: c , Wsave
integer :: iw1 , iw2 , n
dimension c(*) , Wsave(*)
if ( n==1 ) return
iw1 = n + n + 1
iw2 = iw1 + n + n
call cfftb1(n,c,Wsave,Wsave(iw1),Wsave(iw2))
end subroutine zfftb
