# 1 "<stdin>"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "<stdin>"
module polydiv
! Helix polynomial division
  use adj_mod
  use helix
  implicit none
  integer, private :: nd
  type( filter), private :: aa
  real ,private, dimension (:), allocatable :: tt
  contains
  subroutine polydiv_init ( nd_in,aa_in )
    integer :: nd_in
    type( filter) :: aa_in
    nd = nd_in
    aa = aa_in
    if (.not. allocated(tt)) then
      allocate(tt ( nd))
    end if
  end subroutine
  function polydiv_lop ( adj, add, xx, yy) result(stat)
    integer :: stat
    logical,intent(in) :: adj,add
    real,dimension(:) :: xx,yy
    call adjnull (adj,add,xx,yy )
    call polydiv_lop2(adj,add,xx,yy )
    stat=0
  end function
  subroutine polydiv_lop2(adj,add,xx,yy)
    logical,intent(in) :: adj,add
    real, dimension (:) :: xx
    real, dimension (:) :: yy
    integer ia, ix, iy
    tt = 0.
    if ( adj) then
      do ix= nd, 1, -1
        tt( ix) = yy( ix)
        do ia = 1, size( aa%lag)
          iy = ix + aa%lag( ia)
          if ( iy > nd) then
            cycle
          end if
          tt( ix) = tt( ix) - aa%flt( ia) * tt( iy)
        end do
      end do
      xx = xx + tt
    else
      do iy= 1, nd
        tt( iy) = xx( iy)
        do ia = 1, size( aa%lag)
          ix = iy - aa%lag( ia)
          if ( ix < 1) then
            cycle
          end if
          tt( iy) = tt( iy) - aa%flt( ia) * tt( ix)
        end do
      end do
      yy = yy + tt
    end if
  end subroutine
  subroutine polydiv_close()
    deallocate( tt )
  end subroutine
end module