Fig. 3.

The effect of iteration. A 10 mm source is simulated and IRES estimation at each iteration, is depicted. As it can be seen the estimated solution converges to the final solution after a few iterations and more so the continuation of the iterations does not affect the solution, i.e. shrink it. The bottom right graph shows the norm of the solution (blue) and the gradient of the solution (green) and also the goal function (red) at each iteration. The goal function (penalizing terms) is the term minimized in (2).