module invstack {
	use imospray
	use cgstep_mod
	use simple_solver
contains
	# NMO stack by inverse of forward modeling
	subroutine stack( nt, model, nx, gather,     t0,x0,dt,dx,slow, niter) {
	integer           nt,        nx,                               niter
	real                  model (:), gather (:), t0,x0,dt,dx,slow

	call imospray_init( slow, x0,dx, t0,dt, nt, nx)

	call solver( imospray_lop, cgstep, model, gather, niter)

	call cgstep_close ();  call imospray_close ()   # garbage collection
	}
}