use bitmasks

! BEGIN_PROVIDER [ integer(bit_kind), psi_ref, (N_int,2,psi_det_size) ]
!&BEGIN_PROVIDER [ double precision, psi_ref_coef,  (psi_det_size,n_states) ]
!&BEGIN_PROVIDER [ integer, idx_ref, (psi_det_size) ]
!&BEGIN_PROVIDER [ integer, N_det_ref ]
!  implicit none
!  BEGIN_DOC
!  ! Reference wave function, defined as determinants with amplitudes > 0.05
!  ! idx_ref gives the indice of the ref determinant in psi_det.
!  END_DOC
!  integer                        :: i, k, l
!  logical                        :: good
!  double precision, parameter    :: threshold=0.01d0
!  double precision               :: t(N_states)
!  N_det_ref = 0
!  do l = 1, N_states
!    t(l) = threshold * abs_psi_coef_max(l)
!  enddo
!  do i=1,N_det
!    good = .False.
!    do l=1, N_states
!     psi_ref_coef(i,l) = 0.d0
!     good = good.or.(dabs(psi_coef(i,l)) > t(l))
!    enddo
!    if (good) then
!      N_det_ref = N_det_ref+1
!      do k=1,N_int
!        psi_ref(k,1,N_det_ref) = psi_det(k,1,i)
!        psi_ref(k,2,N_det_ref) = psi_det(k,2,i)
!      enddo
!      idx_ref(N_det_ref) = i
!      do k=1,N_states
!        psi_ref_coef(N_det_ref,k) = psi_coef(i,k)
!      enddo
!    endif
!  enddo
!  call write_int(output_determinants,N_det_ref, 'Number of determinants in the reference')
!
!END_PROVIDER

 BEGIN_PROVIDER [ integer(bit_kind), psi_ref, (N_int,2,psi_det_size) ]
&BEGIN_PROVIDER [ double precision, psi_ref_coef,  (psi_det_size,n_states) ]
&BEGIN_PROVIDER [ integer, idx_ref, (psi_det_size) ]
&BEGIN_PROVIDER [ integer, N_det_ref ]
  implicit none
  BEGIN_DOC
  ! Reference wave function, defined as determinants with amplitudes > 0.05
  ! idx_ref gives the indice of the ref determinant in psi_det.
  END_DOC
  integer                        :: i, k, l
  double precision, parameter    :: threshold=0.01d0

  call find_reference(threshold, N_det_ref, idx_ref)
  do l=1,N_states
    do i=1,N_det_ref
      psi_ref_coef(i,l) = psi_coef(idx_ref(i), l)
    enddo
  enddo
  do i=1,N_det_ref
    psi_ref(:,:,i) = psi_det(:,:,idx_ref(i))
  enddo
  call write_int(output_determinants,N_det_ref, 'Number of determinants in the reference')

END_PROVIDER