===firstname: Ian ===firstname3: ===affil6: ===lastname3: ===email: i.n.zwaan@tue.nl ===keyword_other2: ===lastname6: ===affil5: ===lastname4: ===lastname7: ===affil7: ===postal: Department of Mathematics and Computer Science Eindhoven University of Technology PO Box 513 NL-5600 MB Eindhoven The Netherlands ===ABSTRACT: Tikhonov regularization is a popular method to approximate solutions of linear discrete ill-posed problems when the observed or measured data is contaminated by noise. Multi-parameter Tikhonov regularization may improve the quality of the computed approximate solutions. We propose a new iterative method for large-scale multi-parameter Tikhonov regularization with general regularization operators based on a multidirectional subspace expansion. This expansion may be combined with subspace truncation to avoid excessive growth of the search space. Furthermore, we introduce a simple and effective parameter selection strategy based on the discrepancy principle and related to perturbation results. ===affil3: ===title: Multidirectional subspace expansion for single-parameter and multi-parameter Tikhonov regularization ===affil2: Eindhoven University of Technology ===lastname2: Hochstenbach ===firstname4: ===keyword1: Inverse problems, regularization ===workshop: no ===lastname: Zwaan ===firstname5: ===keyword2: Iterative methods in imaging ===otherauths: ===affil4: ===competition: yes ===firstname7: ===firstname6: ===keyword_other1: ===lastname5: ===affilother: ===firstname2: Michiel E.