On the second order asymptotical regularization of linear ill-posed inverse problems
For researchers in inverse problems, this provides a new regularization method with proven convergence rates and practical advantages, though it is an incremental extension of existing asymptotical regularization.
This paper introduces the Second Order Asymptotical Regularization (SOAR) method for solving linear ill-posed inverse problems, proving it achieves the same convergence rates as classical asymptotical regularization under standard conditions, and proposing a new discrepancy principle for optimal rates. Numerical examples demonstrate accuracy and acceleration compared to state-of-the-art methods.
In this paper, we establish an initial theory regarding the Second Order Asymptotical Regularization (SOAR) method for the stable approximate solution of ill-posed linear operator equations in Hilbert spaces, which are models for linear inverse problems with applications in the natural sciences, imaging and engineering. We show the regularizing properties of the new method, as well as the corresponding convergence rates. We prove that, under the appropriate source conditions and by using Morozov's conventional discrepancy principle, SOAR exhibits the same power-type convergence rate as the classical version of asymptotical regularization (Showalter's method). Moreover, we propose a new total energy discrepancy principle for choosing the terminating time of the dynamical solution from SOAR, which corresponds to the unique root of a monotonically non-increasing function and allows us to also show an order optimal convergence rate for SOAR. A damped symplectic iterative regularizing algorithm is developed for the realization of SOAR. Several numerical examples are given to show the accuracy and the acceleration affect of the proposed method. A comparison with other state-of-the-art methods are provided as well.