Tensor-Structured Preconditioners and Approximate Inverse of Elliptic Operators in ℝd

By Boris N. Khoromskij. 2009

69 citations recorded by the source corpus.

AbstractIn the present paper we analyze a class of tensor-structured preconditioners for the multidimensional second-order elliptic operators in ℝd, d≥2. For equations in a bounded domain, the construction is based on the rank-R tensor-product approximation of the elliptic resolvent ℬR≈(ℒ−λI)−1, where ℒ is the sum of univariate elliptic operators. We prove the explicit estimate on the tensor rank R that ensures the spectral equivalence. For equations in an unbounded domain, one can utilize the tensor-structured approximation of Green’s kernel for the shifted Laplacian in ℝd, which is well developed in the case of nonoscillatory potentials. For the oscillating kernels e−iκ‖x‖/‖x‖, x∈ℝd, κ∈ℝ+, we give constructive proof of the rank-O(κ) separable approximation. This leads to the tensor representation for the discretized 3D Helmholtz kernel on an n×n×n grid that requires only O(κ |log ε|2  n) reals for storage. Such representations can be applied to both the 3D volume and boundary calculations with sublinear cost O(n2), even in the case κ=O(n).Numerical illustrations demonstrate the efficiency of low tensor-rank approximation for Green’s kernels e−λ‖x‖/‖x‖, x∈ℝ3, in the case of Newton (λ=0), Yukawa (λ∈ℝ+), and Helmholtz (λ=iκ, κ∈ℝ+) potentials, as well as for the kernel functions 1/‖x‖ and 1/‖x‖d−2, x∈ℝd, in higher dimensions d>3. We present numerical results on the iterative calculation of the minimal eigenvalue for the d-dimensional finite difference Laplacian by the power method with the rank truncation and based on the approximate inverse ℬR≈(−Δ)−1, with 3≤d≤50.

Subfields: Computational Mathematics, Computational Mechanics, Computational Theory and Mathematics

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In Computational Mathematics

  1. Boris N. Khoromskij
  2. Ivan V. Oseledets
  3. Venera Khoromskaia
  4. Ivan P. Gavrilyuk
  5. Christoph Schwab
  6. Sergey V. Dolgov
  7. Vladimir A. Kazeev
  8. Heinz-Jürgen Flad

In Computational Mechanics

  1. Boris N. Khoromskij
  2. Ivan P. Gavrilyuk
  3. Ivan V. Oseledets
  4. Venera Khoromskaia
  5. Christoph Schwab
  6. Markus Bachmayr
  7. Heinz-Jürgen Flad
  8. Wolfgang Dahmen

In Computational Theory and Mathematics

  1. Boris N. Khoromskij
  2. Ivan V. Oseledets
  3. Venera Khoromskaia
  4. Ivan P. Gavrilyuk
  5. Christoph Schwab
  6. Sergey V. Dolgov
  7. Heinz-Jürgen Flad
  8. Vladimir A. Kazeev

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