Clemens Hofreither

Contact

Johannes Kepler University Linz
Institute of Computational Mathematics
Science Park 2 - Room 0344-1
Altenberger Straße 69
4040 Linz
Austria/Europe
[+43] (0)732 2468 4067
chofreither@numa.uni-linz.ac.at
PhD thesis
A Non-standard Finite Element Method using Boundary Integral Operators
Supervised by O.Univ.-Prof. Dr. Ulrich Langer. Defended December 2012

Software

Visit the page for some of my research software in Isogeometric Analysis.

Events

I am co-organizer of a series of interdisciplinary workshops taking place yearly since 2012. It is organized jointly by the Institute of Mathematics and Informatics (Bulgarian Academy of Sciences), and the Doctoral Program Numerical Analysis and Symbolic Computation (Johannes Kepler University), as well as other partner institutes depending on the location.

Publications

[31] C. Hofreither. A Black-Box Algorithm for Fast Matrix Assembly in Isogeometric Analysis. Technical Report 2017-2, Institute of Computational Mathematics, JKU Linz, 2017. [ bib | .pdf ]
[30] I. Georgieva and C. Hofreither. On best uniform approximation by low-rank matrices. Linear Algebra and its Applications, 518:159--176, 2017. [ bib | DOI | report ]
[29] C. Hofreither, S. Takacs, and W. Zulehner. A robust multigrid method for Isogeometric Analysis in two dimensions using boundary correction. Computer Methods in Applied Mechanics and Engineering, 316:22--42, 2017. Special Issue on Isogeometric Analysis: Progress and Challenges. [ bib | DOI | report ]
[28] I. Georgieva and C. Hofreither. An algorithm for low-rank approximation of bivariate functions using splines. Journal of Computational and Applied Mathematics, 310:80--91, 2017. [ bib | DOI | report ]
[27] C. Hofreither and S. Takacs. Robust Multigrid for Isogeometric Analysis Based on Stable Splittings of Spline Spaces. Technical Report 2016-2, Institute of Computational Mathematics, JKU Linz, 2016. [ bib | .pdf ]
[26] C. Hofreither, B. Jüttler, G. Kiss, and W. Zulehner. Multigrid methods for isogeometric analysis with THB-Splines. Computer Methods in Applied Mechanics and Engineering, 308:96--112, 2016. [ bib | DOI | report ]
[25] C. Hofreither, U. Langer, and S. Weißer. Convection-adapted BEM-based FEM. ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik, 96(12):1467--1481, 2016. [ bib | DOI ]
[24] C. Hofreither and W. Zulehner. On Full Multigrid Schemes for Isogeometric Analysis. In T. Dickopf, J. M. Gander, L. Halpern, R. Krause, and F. Luca Pavarino, editors, Domain Decomposition Methods in Science and Engineering XXII, pages 267--274. Springer International Publishing, 2016. [ bib | DOI | report ]
[23] I. Georgieva and C. Hofreither. New results on regularity and errors of harmonic interpolation using Radon projections. Journal of Computational and Applied Mathematics, 293:73--81, 2016. Efficient Numerical Methods for Large-scale Scientific Computations. [ bib | DOI ]
[22] I. Georgieva and C. Hofreither. Cubature rules for harmonic functions based on Radon projections. Calcolo, 52(2):153--166, 2015. [ bib | DOI | report ]
[21] I. Georgieva and C. Hofreither. Interpolating solutions of the Poisson equation in the disk based on Radon projections. Journal of Mathematical Analysis and Applications, 423(1):305--317, 2015. [ bib | DOI | report ]
[20] C. Hofreither and W. Zulehner. Mass Smoothers in Geometric Multigrid for Isogeometric Analysis. In J.-D. Boissonnat, A. Cohen, O. Gibaru, C. Gout, T. Lyche, M.-L. Mazure, and L. L. Schumaker, editors, Curves and Surfaces, volume 9213 of Lecture Notes in Computer Science, pages 272--279. Springer International Publishing, 2015. [ bib | DOI | report ]
[19] C. Hofreither and W. Zulehner. Spectral Analysis of Geometric Multigrid Methods for Isogeometric Analysis. In I. Dimov, S. Fidanova, and I. Lirkov, editors, Numerical Methods and Applications, volume 8962 of Lecture Notes in Computer Science, pages 123--129. Springer International Publishing, 2015. [ bib | DOI | report ]
[18] S. Stoykov, C. Hofreither, and S. Margenov. Isogeometric Analysis for Nonlinear Dynamics of Timoshenko Beams. In I. Dimov, S. Fidanova, and I. Lirkov, editors, Numerical Methods and Applications, volume 8962 of Lecture Notes in Computer Science, pages 138--146. Springer International Publishing, 2015. [ bib | DOI | .pdf ]
[17] C. Hofreither, U. Langer, and C. Pechstein. BEM-based Finite Element Tearing and Interconnecting Methods. Electronic Transactions on Numerical Analysis, 44:230--249, 2015. [ bib | report | http ]
[16] C. Hofreither, U. Langer, and C. Pechstein. FETI solvers for non-standard finite element equations based on boundary integral operators. In J. Erhel, M. J. Gander, L. Halpern, G. Pichot, T. Sassi, and O. Widlund, editors, Domain Decomposition Methods in Science and Engineering XXI, volume 98 of Lecture Notes in Computational Science and Engineering, pages 729--737, Heidelberg, Berlin, 2014. Springer. [ bib | DOI | report ]
[15] I. Georgieva and C. Hofreither. Cubature Rules for Harmonic Functions on the Disk Using Line Integrals over Two Sets of Equispaced Chords. In K. Ivanov, G. Nikolov, and R. Uluchev, editors, Constructive Theory of Functions, Sozopol 2013: Dedicated to Blagovest Sendov and Vasil Popov, pages 81--93. Prof. Marin Drinov Academic Publishing House, Sofia, 2014. [ bib ]
[14] I. Georgieva and C. Hofreither. Interpolation of harmonic functions based on Radon projections. Numerische Mathematik, 127(3):423--445, 2014. [ bib | DOI | report ]
[13] I. Georgieva, C. Hofreither, and R. Uluchev. Least Squares Fitting of Harmonic Functions Based on Radon Projections. In M. Floater, T. Lyche, M.-L. Mazure, K. Mørken, and L. L. Schumaker, editors, Mathematical Methods for Curves and Surfaces, volume 8177 of Lecture Notes in Computer Science, pages 158--171. Springer Berlin Heidelberg, 2014. [ bib | DOI | report ]
[12] I. Georgieva, C. Hofreither, and R. Uluchev. Approximations Using Radon Projection Data in the Unit Disk. In G. Akravis et al., editor, Proceedings of NumAn 2014 Conference -- Recent Approaches to Numerical Analysis: Theory, Methods and Applications, pages 116--122, 2014. [ bib ]
[11] C. Hofreither and C. Pechstein. A Rigorous Error Analysis of Coupled FEM-BEM Problems with Arbitrary Many Subdomains. In T. Apel and O. Steinbach, editors, Advanced Finite Element Methods and Applications, volume 66 of Lecture Notes in Applied and Computational Mechanics, pages 109--132. Springer Berlin Heidelberg, 2013. [ bib | DOI | report ]
[10] I. Georgieva, C. Hofreither, C. Koutschan, V. Pillwein, and T. Thanatipanonda. Harmonic interpolation based on Radon projections along the sides of regular polygons. Central European Journal of Mathematics, 11(4):609--620, 2013. [ bib | DOI | report ]
[9] C. Hofreither. A Non-standard Finite Element Method using Boundary Integral Operators. PhD thesis, Johannes Kepler University, Institute of Computational Mathematics, December 2012. [ bib | http ]
[8] C. Hofreither, U. Langer, and C. Pechstein. A Non-standard Finite Element Method Based on Boundary Integral Operators. In I. Lirkov, S. Margenov, and J. Wasniewski, editors, Large-Scale Scientific Computing, volume 7116 of Lecture Notes in Computer Science, pages 28--39. Springer Berlin / Heidelberg, 2012. [ bib | DOI | report ]
[7] I. Georgieva, C. Hofreither, and R. Uluchev. Interpolation of mixed type data by bivariate polynomials. In G. Nikolov and R. Uluchev, editors, Constructive Theory of Functions, Sozopol 2010: In memory of Borislav Bojanov, pages 93--107. Prof. Marin Drinov Academic Publishing House, Sofia, 2012. [ bib | report ]
[6] I. Georgieva and C. Hofreither. An algebraic method for reconstruction of harmonic functions via Radon projections. AIP Conference Proceedings, 1487(1):112--119, 2012. [ bib | DOI | report ]
[5] C. Hofreither. L2 Error Estimates for a Nonstandard Finite Element Method on Polyhedral Meshes. J. Numer. Math., 19(1):27--39, 2011. [ bib | DOI | report ]
[4] C. Hofreither, U. Langer, and C. Pechstein. A Non-standard Finite Element Method for Convection-Diffusion-Reaction Problems on Polyhedral Meshes. In M. D. Todorov and C. I. Christov, editors, Proceedings of the Third Conference of the Euro-American Consortium for Promoting the Application of Mathematics in Technical and Natural Sciences, volume 1404, pages 397--404. AIP Conference Proceedings, 2011. [ bib | DOI ]
[3] I. Georgieva and C. Hofreither. Some Computational Aspects of Harmonic Interpolation Via Radon Projections. In Proceedings of BG SIAM'11, pages 44--49, 2011. [ bib | .pdf ]
[2] C. Hofreither, U. Langer, and S. Tomar. Boundary element simulation of linear water waves in a model basin. In I. Lirkov, S. Margenov, and J. Wasniewski, editors, Large-Scale Scientific Computing: Proceedings of LSSC 2009, pages 132--139. Volume 5910 of Lecture Notes in Computer Science, Springer Verlag, 2010. [ bib | DOI | report ]
[1] C. Hofreither, U. Langer, and C. Pechstein. Analysis of a non-standard finite element method based on boundary integral operators. Electronic Transactions on Numerical Analysis, 37:413--436, 2010. [ bib | report | http ]

Talks

Note: This list is updated only in irregular intervals and may be out of date.

24th International Conference on Domain Decomposition Methods (DD24) (site)
February 6-10, 2017, Longyearbyen, Spitsbergen
New Robust and Efficient Multigrid Methods for Isogeometric Analysis

The Mathematics of Finite Elements and Applications (MAFELAP) 2016 (site)
June 14-17, 2016, London, UK
Robust Multigrid for Isogeometric Analysis based on Subspace Correction

International Conference on Numerical Methods for Scientific Computations and Advanced Applications (site)
May 29-June 2, 2016, Hissarya, Bulgaria
A Robust Multigrid Methods for Isogeometric Analysis based on a Stable Splitting and Subspace Correction

International Conference "Advanced Computing for Innovation" - AComIn 2015 (site)
November 10-11, 2015, Sofia, Bulgaria
Robust Multigrid Methods in Isogeometric Analysis

10th International Conference on Large-Scale Scientific Computations (site)
June 8-12, 2015, Sozopol, Bulgaria
A New Multigrid Smoother for Isogeometric Analysis

Third International Conference on Isogeometric Analysis (IGA 2015) (site)
June 1-3, 2015, Trondheim, Norway
A New Multigrid Smoother for Isogeometric Analysis

Austrian Numerical Analysis Day 2015 (site)
May 6-8, 2015, Linz, Austria
New Multigrid Smoothers for Isogeometric Analysis

International Conference on Computational Methods in Applied Mathematics (site)
September 28-October 4, 2014, Strobl, Austria
Mass-smoothers for Geometric Multigrid in Isogeometric Analysis

Workshop on Approximation Theory, CAGD, Numerical Analysis, and Symbolic Computation (site)
August 25-31, 2014, Sozopol, Bulgaria
The Poisson Equation as an Interpolation Problem Based on Radon Projection

Workshop on Approximation Theory, CAGD, Numerical Analysis, and Symbolic Computation (site)
August 25-31, 2014, Sozopol, Bulgaria
Analysis of Geometric Multigrid Methods for Isogeometric Analysis

8th International Conference on Numerical Methods and Applications (site)
August 20-24, 2014, Borovets, Bulgaria
Spectral Analysis of Geometric Multigrid Methods for Isogeometric Analysis

8th International Conference Curves and Surfaces (site)
June 12-18, 2014, Paris, France
Efficient Geometric Multigrid for Isogeometric Analysis

22nd International Conference on Domain Decomposition Methods (DD22) (site)
September 16-20, 2013, Lugano, Switzerland
On full multigrid schemes for isogeometric analysis

Workshop on Approximation Theory, CAGD, Numerical Analysis, and Symbolic Computation (site)
August 25-30, 2013, Sozopol, Bulgaria
Cubature rules for harmonic functions based on Radon projections

International Conference Constructive Theory of Functions (site)
June 9-15, 2013, Sozopol, Bulgaria
Cubature rules for harmonic functions based on Radon projections

9th International Conference on Large-Scale Scientific Computations (site)
June 3-7, 2013, Sozopol, Bulgaria
Some Results on Multigrid Methods for Isogeometric Analysis

Interdisciplinary workshop on Approximation Theory, Numerical Analysis and Symbolic Computation (site)
August 31-September 5, 2012, Sozopol, Bulgaria
Interpolation and approximation by harmonic polynomials using Radon Projections

Fourth Conference of the Euro-American Consortium for Promoting the Application of Mathematics in Technical and Natural Sciences (AMiTaNS '12) (site)
June 11-16, 2012, St.St. Constantine and Helena, Varna, Bulgaria
FETI Solvers for a Non-standard Finite Element Method Based on Boundary Integral Operators

4th Workshop BEM on the Saar (site)
May 14-16, 2012, Saarbrücken, Germany
Stable Numerical Schemes for Convection-Diffusion Problems using Boundary Integral Operators

83rd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) (site)
March 26-30, 2012, Darmstadt, Germany
A Stabilized Finite Element Method for Convection-Diffusion Problems using Boundary Integral Operators

9th Workshop Fast Boundary Element Methods in Industrial Applications (site)
September 29-October 2, 2011, Söllerhaus, Austria
A BEM–based FEM for convection–diffusion equations

Application of mathematics in technical and natural sciences: 3rd international conference (AMiTaNS '11) (site)
June 20-25, 2011, Albena, Bulgaria
A Non-standard Finite Element Method based on Boundary Integral Operators

82nd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) (site)
April 18-21, 2011, Graz, Austria
Convergence Analysis for a Non-standard Finite Element Method on Polyhedral Meshes

8th Workshop Fast Boundary Element Methods in Industrial Applications (site)
September 30-October 3, 2010, Söllerhaus, Austria
L_2 Error Estimates for a BEM-based FEM

7th International Conference on Numerical Methods and Applications (site)
August 20-24, 2010, Borovets, Bulgaria
A non-standard finite element method based on boundary integral operators

Workshop on Non-Standard Numerical Methods for PDEs (site)
June 29-July 2, 2010, Pavia, Italy
A non-standard finite element method based on boundary integral operators

Söllerhaus Workshop on Domain Decomposition Solvers for Heterogeneous Field Problems (site)
June 2-6, 2010, Söllerhaus, Austria
A non-standard finite element method based on boundary integral operators

6th Austrian Numerical Analysis Day (site)
May 6-7, 2010, Salzburg, Austria
A non-standard finite element method based on boundary integral operators

7th Workshop Fast Boundary Element Methods in Industrial Applications (site)
October 15-18, 2009, Söllerhaus, Austria
Boundary Element based Trefftz Methods for Potential Problems

7th International Conference on Large-Scale Scientific Computing (site)
June 4-8, 2009, Sozopol, Bulgaria
Boundary Element Simulation of Linear Water Waves in a Model Basin