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[Invited Talk]
T. Sogabe and F. Tatsuoka, Recent Developments in Computing Matrix Functions With The Double Exponential Formulas, IV International Conference on Mathematics and its Applications in Science and Engineering, U-Tad, Madrid, Spain, July 12-14, 2023. |
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[Invited Talk]
T. Sogabe and A. Ohashi, Computation of singular values for generalized tensor sum, The 40th JSST Annual International Conference on Simulation Technology, Doshisha University, Kyoto, Japan, Sep. 1-3, 2021 (Online). |
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F. Tatsuoka, T. Sogabe, Y. Miyatake, T. Kemmochi, S.-L. Zhang Computing the matrix fractional power based on the double exponential formula SIAM Conference on Applied Linear Algebra (SIAM LA21), May 17-21 2021. |
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A. Ohashi and T. Sogabe, On computing an arbitrary singular value of a tensor sum, International Conference on Mathematics and its Applications in Science and Engineering (ICMASE2020), Ankara Haci Bayram Veli University, Ankara, Turkey, July 9-10, 2020 (Online). |
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F. Tatsuoka, T. Sogabe, Y. Miyatake, T. Kemmochi, S.-L. Zhang Computing the matrix fractional power based on the double exponential formula SIAM Conference on Applied Linear Algebra (SIAM LA21), May 17-21 2021. |
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Y. Satake, T. Sogabe, T. Kemmochi, and S.-L. Zhang, On the *-congruence Sylvester equation, International Conference on Mathematics and its Applications in Science and Engineering (ICMASE2020), Ankara Haci Bayram Veli University, Ankara, Turkey, July 9-10, 2020 (Online). |
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[Invited Talk]
T. Sogabe, M. Oozawa, Y. Miyatake, and S.-L. Zhang, Relation between T-congruence Sylvester equation and Lyapunov equation, Conference on Mathematical, Physical and Intelligent Sciences 2019, Dalian University of Technology, Panjin, China, June 26-30, 2019. |
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F. Tatsuoka, T. Sogabe, Y. Miyatake, and S.-L. Zhang, On an interval truncation method of the double exponential formula for the matrix logarithm, SIAM East Asian Section Conference 2019, Wuhan University, Wuhan, China, Jun. 13-16, 2019. |
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S. Takahira, A. Ohashi, T. Sogabe, and T. S. Usuda, Quantum algorithm for matrix functions by Cauchy's integral formula, 18th Asian Quantum Information Science Conference (AQIS2018), Nagoya, Extended Abstracts of AQIS2018, 213, Sept. 8-12, 2018. |
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[Invited Talk]
T. Sogabe, D. Lee, and S.-L. Zhang, Recent progress on numerical algorithms for large eigenvalue problems, The workshop on Computational Methods for Eigenvalue Problems, Jilin University, China, Aug. 13-17, 2018. |
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F. Tatsuoka, T. Sogabe, Y. Miyatake, and S.-L. Zhang, Computation of the matrix logarithm using the double exponential formula, Numerical Analysis and Scientific Computation with Applications (NASCA2018), Kalamata, Greece, July 2-6, 2018. |
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F. Tatsuoka, T. Sogabe, Y. Miyatake, and S.-L. Zhang, Computation of the matrix fractional power based on the double exponential formula, SIAM East Asian Section Conference 2018, The University of Tokyo, Tokyo, Japan, June 22-25, 2018. |
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D. Lee, T. Hoshi, T. Sogabe, Y.Miyatake, and S.-L. Zhang, Solving the k-th eigenvalue problem in large-scale electronic structure Calculations, 18th SIAM Conference on Parallel Processing for Scientific Computing, Waseda University, Tokyo, Japan, Mar. 7-10, 2018. |
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K. Yoshimi, M. Kawamura, Y. Yamaji, T. Sogabe, and T. Hoshi, Open-source software development that bridges the gap between numerical analysis and material simulation on supercomputers, 18th SIAM Conference on Parallel Processing for Scientific Computing, Waseda University, Tokyo, Japan, Mar. 7-10, 2018. |
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S. Takahira, A. Ohashi, T. Sogabe, and T. S. Usuda, Amplitude estimation based algorithm for circulant linear systems, 17th Asian Quantum Information Science Conference (AQIS2017), Singapore, Proceedings of AQIS2017, pp. 279-281, Sept. 4-8, 2017. |
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Y. Miyatake, T. Sogabe, S.-L. Zhang, On the equivalence between the SOR-type methods and the Itoh-Abe discrete gradient methods, SIAM: East Asian Section Conference 2017, Seoul, South Korea, June 21-25, 2017. |
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D. Lee, T. Hoshi, Y. Miyatake, T. Sogabe, and S.-L. Zhang, An eigenvalue problem in electronic structure calculations and its solution by spectrum slicing, SIAM: East Asian Section Conference 2017, Seoul, South Korea, June 21-25, 2017. |
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A fast and stable Incremental Newton iteration for the matrix pth root, F.Tatsuoka, T. Sogabe, Y. Miyatake, and S.-L. Zhang, SIAM: East Asian Section Conference 2017, Seoul, South Korea, June 21-25, 2017. |
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(Requested to give a talk)
Y. Miyatake, T. Sogabe, S.-L. Zhang, Iterative solvers based on the discrete gradient method for symmetric positive definite linear systems, 19h International Conference on Finite Elements in Flow Problems - FEF 2017, Rome, Italy, April 5-7, 2017. |
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S. Takahira, A. Ohashi, T. Sogabe, and T. S. Usuda, Quantum algorithm for linear equations with a circulant matrix, 16th Asian Quantum Information Science Conference (AQIS'16), Taipei, Taiwan, Aug. 28 - Sept. 2, 2016. |
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D. Lee, T. Hoshi, Y. Miyatake, T. Sogabe, and S.-L. Zhang, A bisection approach combined with a projection method for interior eigen-value problems in materials science, SIAM: East Asian Section Conference 2016 (EASIAM2016), Macau, China, Jun. 20-22, 2016. |
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[Plenary Talk] T. Sogabe and S.-L. Zhang, A block Krylov subspace method for shifted linear systems with complex symmetric matrices, International Conference on Information and Computational Science (ICICS2016), Dalian University of Technology, Dalian, China, Aug. 2-6, 2016. |
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[Invited Talk] T. Sogabe, Krylov subspace methods for complex symmetric linear systems, Workshop on Numerical Algebra, Algorithms, and Analysis, National Institute of Informatics, Tokyo, Japan, Jan. 11-12, 2016. |
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[Invited Talk] T. Sogabe and S.-L. Zhang, A block variant of the COCG method for generalized shifted linear systems with multiple right-hand sides, 13th U.S. National Congress on Computational Mechanics (USNCCM13), Manchester Grand Hyatt, San Diego, CA., USA, July 26-30, 2015. |
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S. Takahira, A. Ohashi, T. Sogabe, and T. S. Usuda, Quantum-classical hybrid algorithm to solve linear equations for k-tridiagonal matrix, 15th Asian Quantum Information Science Conference (AQIS2015), Proceedings of AQIS2015, pp. 154-155, Aug. 2015. |
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M. Tanaka, A. Ohashi, T. Sogabe, and T. S. Usuda, Derivation of analytical expression of channel matrix for coded 4PSK signals using tensor product decomposition of Gram matrix, 15th Asian Quantum Information Science Conference (AQIS2015), Korea, Proceedings of AQIS2015, pp. 143-144, Aug. 2015. |
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S. Mizuno, Y. Moriizumi, T. S. Usuda, and T. Sogabe, On an initial guess of Newton's method for the matrix square root based on a sphere constrained optimization problem, International Workshop on Information Technology, Applied Mathematics and Science, Kyoto, Japan, Feb., 2015. |
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T. S. Usuda, T. Sogabe, and K. Shiromoto, Formula of channel matrix for covariant signal set with respect to a direct product of groups, 12th International Conference on Quantum Communication, Measurement and Computing (QCMC2014), Hefei, China, Nov. 2014. |
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M. Tanaka, T. Sogabe, K. Shiromoto, and T. S. Usuda, Group covariance and formula of channel matrix of coded 4PSK signals by linear codes over F4, 2014 International Symposium on Information Theory and Its Applications (ISITA2014), Melbourne, Australia, Oct. 2014. |
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[Invited Talk]
A. Ohashi and T. Sogabe, An algorithm for computing extremal singular values of a generalized tensor sum, Structured Numerical Linear and Multilinear Algebra: Analysis, Algorithms and Applications (SLA2014), Kalamata, Greece, September 8-12, 2014, |
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T. Sogabe and S.-L. Zhang, “An iterative method for solving complex symmetric generalized shifted linear systems with multiple right-hand sides”, The 4th International Conference on Matrix Analysis and Applications, Dedeman Hotel, Konya, Turky, July 2-5, 2013. |
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A. Ohashi and T. Sogabe On computing maximum/minimum singular values of a generalized tensor sum, Numerical Analysis and Scientific Computation with Applications (NASCA13) , Universite du Littoral Cote d'Opale, Calais, France, June 24-26, 2013. |
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T. Hoshi, T. Sogabe, S.-L. Zhang, and H. Imachi, Krylov subspace theories and one-hundred-million-atom quantum material simulations on the K computer, International Workshop on Eigenvalue Problems: Algorithms; Software and Applications, in Petascale Computing (EPASA2014) Tsukuba International Congress Center EPOCHAL TSUKUBA,Tsukuba-city,Japan, March 7-9, 2014. (poster) |
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D. Lee, T.Miyata, T. Sogabe, T. Hoshi, and S.-L. Zhang, A numerical approach to obtaining intermediate eigenvalues in electronic structure calculations, International Symposium on Computics: Quantum Simulation and Design (ISC-QSD), Osaka University Hall, Oct. 11-13, 2012. (poster) |
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T. Sogabe, T. Hoshi, S.-L. Zhang, T. Fujiwara, "Krylov subspace methods for generalized shifted linear systems arising in large-scale electronic structure calculation", International Symposium on Computics: Quantum Simulation and Design (ISC-QSD), Osaka University Hall, Oct. 11-13, 2012. |
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[Invited Talk]
T. Hoshi, S. Yamamoto, T. Fujiwara, T. Sogabe, S-L. Zhang, Y. Akiyama, T. Ohno, "Ten-million-atom electronic structure calculations with novel linear-algebraic algorithm and the K computer", International Symposium on Computics: Quantum Simulation and Design (ISC-QSD), Osaka University Hall, Oct. 11-13, 2012. |
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[Invited Talk]
T. Sogabe, T. Hoshi, S.-L. Zhang and T. Fujiwara, "Numerical methods for generalized shifted linear systems with complex symmetric matrices", 4th China-Japan-Korea Conference on Numerical Mathematics, Otsu City, Shiga Prefecture, Japan, August 25-28, 2012. |
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T. Miyata, T. Sogabe, and S.-L. Zhang, “Jacobi-Davidson Type Methods Using a Shift Invariance Property of Krylov Subspaces for Eigenvalue Problems”, SIAM Conference on Applied Linear Algebra, Valencia, Spain, June 18, 2012. |
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[Invited Talk]
T. Sogabe, T. Hoshi, S.-L. Zhang and T. Fujiwara, "Krylov subspace methods for solving generalized shifted linear systems", International Workshop on Computational Science and Numerical Analysis, The University of Electro-Communications, Tokyo, Japan, March 24-26, 2012. |
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[Invited Talk]
T. Hoshi, T. Sogabe, S. Yamamoto, S. Nishino, T. Fujiwara, S.-L. Zhang and Y. Yamamoto, "Novel linear-algebraic theories in large-scale electronic structure calculation and its application to nano-materials", Dresden-Kobe Joint Workshop on Electronic Simulations for Nanosystems, Kobe University, Japan, March 7, 2012. |
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L. Du, T. Sogabe, S.-L. Zhang, "A variant of the IDR(s) method with quasi-minimal residual strategy", The 7th East Asia SIAM Conference & RIMS Workshop on Methods in Industrial and Applied Mathematics, Waseda University Kitakyushu Campus, Japan, June 27-29, 2011. |
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T. Miyata, L. Du, T. Sogabe, Y. Yamamoto, S.-L. Zhang, "A projection approach to complex eigenvalues of a specified absolute value", The 7th East Asia SIAM Conference & RIMS Workshop on Methods in Industrial and Applied Mathematics, Waseda University Kitakyushu Campus, Japan, June 27-29, 2011. |
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T. Hoshi, T. Fujiwara, Y. Zempo, M. Ishida, S. Yamamoto, S. Nishino, T. Sogabe, S.-L. Zhang, "Large scale electronic structure calculations with ELSES", IPsi-k Conference 2010, Berlin, Germany, September 12-16, 2010. |
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T. Sogabe, A. Suzuki, and S.-L. Zhang, "On a cost-efficient iteration of Ye’s hybrid method for minimizing a quadratic function over a sphere constraint", 2nd IMA Conference on Numerical Linear Algebra and Optimisation, p.16, University of Birmingham, UK, Sep. 13-15, 2010. |
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[Invited Talk]
S.-L. Zhang, A. Imakura, and T. Sogabe, "GMRES(m) Method with Look-Back-type Restart for Solving Nonsymmetric Linear Systems", The 7th International Conference on Scientific Computing and Application, Dalian, China, June 13-16, 2010. |
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[Invited Talk]
A. Imakura, T. Sogabe and S.-L. Zhang, "A Look-Back Technique of Restart for the GMRES(m) Method", Applied Linear Algebra - in honor of Hans Schneider, University of Novi Sad, Novi Sad, Serbia, May 24-28, 2010. |
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A. Imakura, T. Sogabe, and S.-L. Zhang, "A look-back strategy for the GMRES(m) method", The 7th International Conference on Numerical Optimization and Numerical Linear Algebra, P. 31, Lijiang, Yunnan, China, Aug. 16-19, 2009 |
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T. Miyata, L. Du, T. Sogabe, Y. Yamamoto, and S.-L. Zhang, "Computation of eigenvalues in multiply connected region", The 7th International Conference on Numerical Optimization and Numerical Linear Algebra, P. 38, Lijiang, Yunnan, China, Aug. 16-19, 2009 |
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T. Sogabe and S.-L. Zhang, "A fast solver for generalized shifted linear systems with complex symmetric matrices", The 7th International Conference on Numerical Optimization and Numerical Linear Algebra, P. 41, Lijiang, Yunnan, China, Aug. 16-19, 2009 |
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S.-L. Zhang, A. Imakura, and T. Sogabe, "A new variant of the GMRES(m) method for solving nonsymmetric linear systems", The 2nd International Conference in Mathematical Modelling and Computation and The 5th East Asia SIAM Conference, P.52, Universiti Brunei Darussalam, Brunei, June 8-11, 2009. |
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T. Sogabe and S.-L. Zhang, "An approach to fast solution of generalized shifted linear systems with complex symmetric matrices", Numerical Analysis and Scientific Computing with Applications (NASCA2009), p. 82, Agadir, Morocco, May 18-22, 2009. |
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A. Imakura, T. Sogabe, and S.-L. Zhang, "An efficient variant of the GMRES(m) method based on error equations", Numerical Analysis and Scientific Computing with Applications (NASCA2009), p. 52, Agadir, Morocco, May 18-22, 2009. |
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T. Hoshi, S. Yamamoto, T. Sogabe, S.-L. Zhang and T. Fujiwara, "Novel algorithms for large-scale shifted linear equations based on Krylov subspace theory", Supercomputing in Solid State Physics , ISSP, Univ. of Tokyo, Feb. 16-19, 2009. (Poster) |
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[Invited Talk]
S.-L. Zhang and T. Sogabe, "Numerical Algorithms for Solving Shifted Complex Symmetric Linear Systems", The NIMS 2008 Conference & The 4th East Asia SIAM Conference, Daejeon, Korea, Oct. 10-12, 2008. |
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S. Yamamoto, T. Sogabe, T. Hoshi, S.-L. Zhang, and T. Fujiwara "Extra large size linear problem solver and its application to the excitation spectra in the many-electron problem", International Conference on Quantum Simulators and Design 2008, Tokyo, Japan, May 31-Jun. 3, 2008. (Poster presentation) |
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[Winner among young researchers]
A. Imakura, T. Sogabe, and S.-L. Zhang, "Implicit wavelet sparse approximate inverse preconditioner using blocked finger pattern for nonsymmetric linear systems", ALA 2008 Applied Linear Algebra-in honor of Ivo Marek, Novi Sad, Serbia, Apr. 28-30, 2008. |
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[Invited Talk]
T. Hoshi, T. Sogabe, S.-L. Zhang, S. Yamamoto, H. Nitta, N. Watanabe,
Y. Zempo and T. Fujiwara, "Novel linear-algebraic algorithm and large-scale electronic structure calculation", 2008 International Workshop on Riken-Harvard GPGPU Symposium 2008, Harvard University, USA, 2008.3. |
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[Invited Talk]
T. Sogabe, T. Hoshi, S.-L. Zhang, and T. Fujiwara, "A numerical approach to the computation of Green's function in large-scale electronic structure theory", 2008 International Workshop on Numerical Verification and its Applications (INVA2008), Okinawa, Japan, 2008.3. |
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[Invited Talk]
T. Sogabe, T. Hoshi, S.-L. Zhang, and T. Fujiwara, "On an application of the QMR method to complex symmetric shifted linear systems", International Workshop on Large-scale Matrix Computation and Applications in Physics and Engineering Science, Tokyo, Japan, 2007.12. |
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[Invited Talk]
T. Sogabe and S.-L. Zhang, "Recent development of Krylov subspace methods for the solution of complex symmetric shifted linear systems", International Conference on Numerical Optimization and Numerical Linear Algebra, p. 7, Urumqi, XinJiang, China, 2007.9. |
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T. Sogabe and S.-L. Zhang, "On a weighted quasi-residual minimization strategy of QMR for solving complex symmetric shifted linear systems", Harrachov 2007-Computational Methods with Applications-, p. 92, Harrachov, Czech Republic, 2007.8. |
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T. Sogabe, T. Hoshi, S.-L. Zhang, and T. Fujiwara, "Krylov subspace methods for solving complex symmetric shifted linear systems", The 6th International Congress on Industrial and Applied Mathematics (ICIAM07), Zurich, Switzerland, 2007.7. |
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T. Sogabe and S.-L. Zhang, "Sparse approximate inverse preconditioners for complex symmetric systems of linear equations", 2007 International Conference on Preconditioning Techniques for Large Sparse Matrix Problems in Scientific and Industrial Applications (Precond 2007), pp. 90-93, Toulouse, France, 2007.7. |
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T. Sogabe, M. Sugihara, and S.-L. Zhang, "Bi-conjugate residual method for nonsymmetric linear systems", The First International Conference on Numerical Algebra and Scientific Computing (NASC06), pp.30-31, Beijing, China, 2006.10. |
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T. Sogabe and S.-L. Zhang, "CRS: a fast algorithm based on Bi-CR for solving nonsymmetric linear systems", The First China-Japan-Korea Joint Conference on Numerical Mathematics, Sapporo, Japan, 2006.8. |
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H. Hasegawa. T. Sogabe, T. Ogita, and T. Kajiyama, "Comparison of conjugate gradient method for nonsymmetric matrices", The Joint GAMM-SIAM Conference on Applied Linear Algebra (ALA2006), Dusseldorf, Germany, 2006.7. |
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[Invited Talk]
T. Sogabe, T. Hoshi, S.-L. Zhang, and T. Fujiwara, A numerical method for calculating the Green's function arising from electronic structure theory, International Symposium on Frontiers of Computational Science (FCS2005), p. 32, Nagoya, Japan, 2005.12. |
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T. Sogabe and S.-L. Zhang, "COCR methods for solving complex symmetric linear systems", 11th GAMM - IMACS International Symposium on Scientific Computing, Computer Arithmetic, and Validated Numerics (SCAN2004), p. 107, Fukuoka, Japan, 2004.10. |
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[Invited Talk] S.-L. Zhang and T. Sogabe, "An extension of the conjugate residual method to nonsymmetric linear systems", The 7th China-Japan Joint Seminar for Computational Mathematics and Scientific Computing, Zhang Jia Jie, China, 2004.8. |
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[Plenary Talk] S.-L. Zhang and T. Sogabe (speaker), "The Bi-CR method for nonsymmetric linear systems", International Conference on Numerical Linear Algebra and Optimization (ICNLAO2003), p. 19, GuiLin, China, 2003.10. |
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T. Sogabe, C.-H. Jin, K. Abe, and S.-L. Zhang, "On the improvement of the CGS method", The 5th International Congress on Industrial and Applied Mathematics (ICIAM2003), p. 97, Sydney, Australia, 2003.7. |