module misif {  # MISSIF -- find MISSing Input data and Filter 
  use peftc
  use tcai1
  use cgstep_mod
  use solver_mod
contains
  subroutine misif1 (niter, xx, aa, mm) {
    integer, intent (in)                               :: niter  # iterations
    real,    dimension (:)                             :: xx, aa # data, PEF
    logical, dimension (:)                             :: mm     # mask
    real,    dimension (:), pointer                    :: xk, bb
    real,    dimension (size (xx) + size (aa))         :: dat
    real,    dimension (size (xx) + size (aa)), target :: x
    integer                                            :: nx
    nx = size (xx)
    x = 0.; dat = 0.	
    xk => x (1 : nx  ) ; where (mm (1 : nx )) xk = xx
    bb => x (1 + nx :) ; where (mm (1 + nx:)) bb = 1.
    call peftc_init (bb, xk)
    call solver (peftc_lop, cgstep, niter = niter, x0 = x, x = x, 
                 dat = dat, nloper = tcai1_lop, known = mm)
    call cgstep_close ()
    xx = xk ; aa = bb
  }
}