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Cell centered Galerkin methods for diffusive problems

Daniele A. Di Pietro (2012)

ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique

In this work we introduce a new class of lowest order methods for diffusive problems on general meshes with only one unknown per element. The underlying idea is to construct an incomplete piecewise affine polynomial space with optimal approximation properties starting from values at cell centers. To do so we borrow ideas from multi-point finite volume methods, although we use them in a rather different context. The incomplete polynomial space replaces classical complete polynomial spaces in discrete...

Cell centered Galerkin methods for diffusive problems

Daniele A. Di Pietro (2011)

ESAIM: Mathematical Modelling and Numerical Analysis

In this work we introduce a new class of lowest order methods for diffusive problems on general meshes with only one unknown per element. The underlying idea is to construct an incomplete piecewise affine polynomial space with optimal approximation properties starting from values at cell centers. To do so we borrow ideas from multi-point finite volume methods, although we use them in a rather different context. The incomplete polynomial space replaces classical complete polynomial spaces...

Colouring polytopic partitions in d

Michal Křížek (2002)

Mathematica Bohemica

We consider face-to-face partitions of bounded polytopes into convex polytopes in d for arbitrary d 1 and examine their colourability. In particular, we prove that the chromatic number of any simplicial partition does not exceed d + 1 . Partitions of polyhedra in 3 into pentahedra and hexahedra are 5 - and 6 -colourable, respectively. We show that the above numbers are attainable, i.e., in general, they cannot be reduced.

Combined a posteriori modeling-discretization error estimate for elliptic problems with complicated interfaces

Sergey I. Repin, Tatiana S. Samrowski, Stéfan A. Sauter (2012)

ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique

We consider linear elliptic problems with variable coefficients, which may sharply change values and have a complex behavior in the domain. For these problems, a new combined discretization-modeling strategy is suggested and studied. It uses a sequence of simplified models, approximating the original one with increasing accuracy. Boundary value problems generated by these simplified models are solved numerically, and the approximation and modeling errors are estimated by a posteriori estimates of...

Combined a posteriori modeling-discretization error estimate for elliptic problems with complicated interfaces

Sergey I. Repin, Tatiana S. Samrowski, Stéfan A. Sauter (2012)

ESAIM: Mathematical Modelling and Numerical Analysis

We consider linear elliptic problems with variable coefficients, which may sharply change values and have a complex behavior in the domain. For these problems, a new combined discretization-modeling strategy is suggested and studied. It uses a sequence of simplified models, approximating the original one with increasing accuracy. Boundary value problems generated by these simplified models are solved numerically, and the approximation and modeling errors are estimated by a posteriori estimates of...

Combined a posteriori modeling-discretization error estimate for elliptic problems with complicated interfaces

Sergey I. Repin, Tatiana S. Samrowski, Stéfan A. Sauter (2012)

ESAIM: Mathematical Modelling and Numerical Analysis

We consider linear elliptic problems with variable coefficients, which may sharply change values and have a complex behavior in the domain. For these problems, a new combined discretization-modeling strategy is suggested and studied. It uses a sequence of simplified models, approximating the original one with increasing accuracy. Boundary value problems generated by these simplified models are solved numerically, and the approximation and modeling errors are estimated by a posteriori estimates of...

Complementarity - the way towards guaranteed error estimates

Vejchodský, Tomáš (2010)

Programs and Algorithms of Numerical Mathematics

This paper presents a review of the complementary technique with the emphasis on computable and guaranteed upper bounds of the approximation error. For simplicity, the approach is described on a numerical solution of the Poisson problem. We derive the complementary error bounds, prove their fundamental properties, present the method of hypercircle, mention possible generalizations and show a couple of numerical examples.

Complexity of an algorithm for solving saddle-point systems with singular blocks arising in wavelet-Galerkin discretizations

Radek Kučera (2005)

Applications of Mathematics

The paper deals with fast solving of large saddle-point systems arising in wavelet-Galerkin discretizations of separable elliptic PDEs. The periodized orthonormal compactly supported wavelets of the tensor product type together with the fictitious domain method are used. A special structure of matrices makes it possible to utilize the fast Fourier transform that determines the complexity of the algorithm. Numerical experiments confirm theoretical results.

Complexity of the method of averaging

Dalík, Josef (2010)

Programs and Algorithms of Numerical Mathematics

The general method of averaging for the superapproximation of an arbitrary partial derivative of a smooth function in a vertex a of a simplicial triangulation 𝒯 of a bounded polytopic domain in d for any d 2 is described and its complexity is analysed.

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