460 citations · 1.2k across the 40 of their papers we have counts for
11 papers · 1 filter
Enhanced attenuation modelling for multispectral computed tomography
Jürgen Jeschke, Dirk Lorenz
We revisit the modelling of the material decomposition problem in multispectral computed tomography and propose to leverage the known absorption spectra of different materials. Wit…
Linearly convergent adjoint free solution of least squares problems by random descent
Dirk A. Lorenz, Felix Schneppe, Lionel Tondji
We consider the problem of solving linear least squares problems in a framework where only evaluations of the linear map are possible. We derive randomized methods that do not need…
Faster Randomized Block Sparse Kaczmarz by Averaging
Lionel Tondji, Dirk A Lorenz
The standard randomized sparse Kaczmarz (RSK) method is an algorithm to compute sparse solutions of linear systems of equations and uses sequential updates, and thus, does not take…
Extended Randomized Kaczmarz Method for Sparse Least Squares and Impulsive Noise Problems
Frank Schöpfer, Dirk A Lorenz, Lionel Tondji +1
The Extended Randomized Kaczmarz method is a well known iterative scheme which can find the Moore-Penrose inverse solution of a possibly inconsistent linear system and requires onl…
Regularization of Inverse Problems by Filtered Diagonal Frame Decomposition
Andrea Ebner, Jürgen Frikel, Dirk Lorenz +2
The characteristic feature of inverse problems is their instability with respect to data perturbations. In order to stabilize the inversion process, regularization methods have to…
The Randomized Kaczmarz Method with Mismatched Adjoint
Dirk A. Lorenz, Sean Rose, Frank Schöpfer
This paper investigates the randomized version of the Kaczmarz method to solve linear systems in the case where the adjoint of the system matrix is not exact---a situation we refer…