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This note is devoted to preconditioning strategies for non-Hermitian multilevel block Toeplitz linear systems associated with a multivariate Lebesgue integrable matrix-valued symbol. In particular, we consider special preconditioned matrices, where the preconditioner has a band multilevel block Toeplitz structure, and we complement known results on the… (More)
Fractional partial order diffusion equations are a generalization of classical partial differential equations, used to model anomalous diffusion phenomena. When using the implicit Euler formula and the shifted Grünwald formula, it has been shown that the related discretizations lead to a linear system whose coefficient matrix has a Toeplitz-like structure.… (More)
are updated because we realised that Pwb can evaluate the SHIA model faster for network sizes of 2 and 4, and also can handle network size of 8.
This paper is concerned with the image deconvolution problem. For the basic model, where the convolution matrix can be diagonalized by discrete Fourier transform, the Tikhonov regularization method is computationally attractive since the associated linear system can be easily solved by fast Fourier transforms. On the other hand, the provided solutions are… (More)
We consider the solution of linear systems of equations, arising from the finite element approximation of coupled differential boundary value problems. Letting the fineness parameter tend to zero gives rise to a sequence of large scale structured two-by-two block matrices. We are interested in the efficient iterative solution of the so arising linear… (More)