module nmis2 {
  use nhelicon
  use npolydiv
  use mask1
  use cgstep_mod
  use solver_mod
contains
# fill in missing data by minimizing power out of a given filter.
# by helix magic works in any number of dimensions
  subroutine mis1( niter, xx, aa, known, precon) {
    logical,                intent( in)     :: precon
    integer,                intent( in)     :: niter
    type( nfilter),         intent( in)     :: aa
    logical, dimension( :), intent( in)     :: known
    real,    dimension( :), intent( in out) :: xx
    real,    dimension( :), allocatable     :: dd
    logical, dimension( :), pointer         :: kk
    integer                                 :: nx
    nx = size( xx)
    if( precon) {                          #  KP p = K y,   m = P p
       allocate( kk( nx)); kk = known
       call mask1_init( kk)
       call npolydiv_init( nx, aa)
       call solver_prec( mask1_lop, cgstep, niter= niter, x= xx, dat= xx, 
         prec= npolydiv_lop, nprec= nx, eps= 0.)
       call npolydiv_close()
       deallocate( kk)
    } else {                               #  KA m = 0
       allocate( dd( nx)); dd = 0.
       call nhelicon_init( aa)
       call solver( nhelicon_lop, cgstep, niter= niter, x= xx, dat= dd, 
                    known = known, x0= xx)
       deallocate( dd)
    }
    call cgstep_close( )
  }
}