module grad2fill {   # min r(m) = L J m + L known  where L is a lowcut filter.
  use igrad2
  use cgstep_mod
  use mask1
  use solver_smp_mod
contains
  subroutine grad2fill2( niter, m1, m2, mm, mfixed) {
    integer,                    intent (in)     :: niter, m1,m2
    logical, dimension (m1*m2), intent (in)     :: mfixed      # mask for known
    real,    dimension (m1*m2), intent (in out) :: mm          # model
    real,    dimension (m1*m2*2)                :: yy          # lowcut output
    logical, dimension (:),     pointer         :: msk

    allocate(msk(size(mfixed)))
    msk=.not.mfixed
    call mask1_init(msk)
    call igrad2_init(m1,m2);                       yy = 0.     # initialize
    call solver_smp(m=mm, d=yy, Fop=igrad2_lop, stepper=cgstep, niter=niter, m0=mm, Jop=mask1_lop)
    call cgstep_close ()
  }
}