EFSTRATIOS GALLOPOULOS | publications | conferences | projects | announcements | links 



Dr. Efstratios Gallopoulos,
Professor and Department Chair
Director, High Performance Information Systems Laboratory
Software Division
Department of Computer Engineering & Informatics
School of Engineering
University of Patras

Research Interests

  • Scientific computing, Parallel and Distributed Processing
  • Linear Algebra and its Applications
  • Computational Science and Engineering
  • Problem Solving Environments
  • Data Mining and Data Analytics


  • Teaching and supervision responsibilities for the following courses: Linear Algebra, Numerical Analysis and Solution Environments, Parallel Processing, Technical Writing and Scientific Presentation, Scientific Computing (4th year), Software and Programming for HPC, Matrix Methods and Tools in Data Science (graduate), Numerical Methods and Tools (graduate), Numerical Analysis and Tools (graduate), Case Studies in Decision Making  (graduate). For more information on courses taught see the Greek home page.


Professor E. Gallopoulos
Dept. Computer Engineering & Informatics

University of Patras
26500 Patras, Greece

Off.: +30(261)0996911, 993805
Fax: +30 (261) 099706
Email:  "gr DOT upatras DOT ceid AT stratis"

University of Patras

Departmental map

Campus map

Biographical sketch (a lengthier CV can be found here): Professor and Chair of the Computer Engineering & Informatics Department (CEID) and Director of the High Performance Information Systems Laboratory. He also serves as director of the interdisciplinary graduate program "Data Driven Computing and Decsion Making". He served as Software Division director for several years (most recently the period 2013-16). In Oct.-Dec. 2016 he was visiting professor at the CS&E Department o the University of Minnesota. Between Nov. 2010-June 2011 he held the position of invited professor and taught at the University of Rennes I (France), and at the University of Padova, Italy. He was also visiting faculty and consultant at the Computer Science Department of Purdue University and INRIA Rennes Bretagne-Atlantique. Prior appointments include research staff and faculty member at the University of Illinois at Urbana-Champaign (1986-96); assistant professor at the University of California Santa Barbara  (1985-86); visiting researcher at NASA Goddard Space Flight Center (summer 1982 & 1983).  He participated as Senior Computer Scientist in research and development of the Cedar vector multiprocessor at the University of Illinois Center for Supercomputing Research and Development (1987-94); participated in the software development of the Goodyear Aerospace Massively Parallel Processor (MPP) (1980-85) receiving a NASA group achievement award  (For outstanding initiative and creativity in the development, demonstration, and practical application of the first Massively Parallel Processor). In  2012, his students and he were awarded the ACM SIGWEB Hypertext Ted Nelson Newcomer Award and in 2016 Springer published the monograph "Parallelism in Matrix Computations" that he co-authored with Bernard Philippe and Ahmed Sameh. His research in Greece has been funded by various European and national programs and in the US by the US National Science Foundation, the US Department of Energy and AT&T. He has been participating as member in scientific committees of numerous international conferences, most recently the 2017 ACM Int'l. Conference on Supercomputing, 2017 ACM Conference on Hypertext and Social Media, ParCo'17, 8th IEEE Int'l. Conference on Big Knowledge, 2018 ACM Conference on Hypertext and Social Media, IEEE ICDM 2019, Euro-EDUPAR 2019, Parco2019. He sat on the editorial boards of several journals (Parallel Computing, International Journal of High Speed Computing, Computing in Science and Engineering) and special issues (Applied Numerical Mathematics, J. Computational and Applied Mathematics), most recently serving on the board of the SIAM Journal of Scientific Computing and of the International Journal of Parallel Programming. He was co-organizer of the 1991 NSF Workshop on Problem Solving Environments, and served as program chair of the 2001 ACM International Conference on Supercomputing and on several occasions in the organizing committee of the NumAn conference. He was a  co-organizer of the 2015 Gene Golub SIAM Summer School on Randomized Numerical Linear Algebra. Dr. Gallopoulos has served as panelist and expert reviewer for various agencies, most notably the European Research Council, the European Commission, and the Ministry of Education and Culture of the Republic of Cyprus. Currently, he is also serving on the SIAM Committee for the Gene Golub Summer School.  Dr. Gallopoulos received his Ph.D. at the Department of Computer Science of the University of Illinois at Urbana-Champaign under the supervision of Daniel Slotnick and his B.Sc. (First Class Honours) in Mathematics from the Imperial College of Science and Technology (1979). He is a member of the ACM and SIAM.

HPCLab activities:

  • Dec. 2017: Congratulations to Vasilis Georgiou and Christos Balkonis for successfully defending their theses and for receiving their Diplomas of Computer Engineering and Informatics during the December commencement exercises. Vasilis' thesis was on "Fast approximation of the inverse of large sparse matrices exploiting their structural properties" and Christos' on "Performance evaluation of parallel applications using 3D or stacked memory". Vasilis is currently following our graduate program and Christos is doing his military service.
  • Dec. 2017: Alumni workshop in Patras.
  • Dec. 2017: Delighted to be hosting our alumnus and Purdue Professor Dr. Petros Drineas (Purdue U.) who delivered an excellent presentation on "Randomization in Numerical Linear Algebra".
  • Oct. 2017: Prof. Gallopoulos has been elected by the faculty to serve as CEID Chair (12/2017-11/2019).
  • Sept. 2017: Received the Best Paper Award for "Factored proximity models for top-N recommendations" presented by Dr. Athanasios (Thanos) Nikolakopoulos at the IEEE Int'l. Conference on Big Knowledge (ICBK) held in Hefei, China. Coauthors of the paper were Vassilis Kalantzis, Prof. John Garofalakis and E. Gallopoulos. It is worth noting that Thanos and Vassilis are currently at the University of Minnesota: Thanos is member of the DTC Lab and Vassilis PhD candidate at the Dept. of CSE. See also our Departmental announcement regarding the award.
  • July 2017: Congratulations to Sotiria Patroni for successfully defending her Diploma Thesis on "Development of clustering algorithms in MATLAB for GPUs". Sotiria will pursue graduate studies at the University of Manchester.
  • March 2017: Congratulations to Aleck Sobczyk for successfully defending his Graduate Diploma Thesis (MDE) entitled "Algorithms for the fast estimation of statistical leverage scores" and to George Kourousias for successfully defending his Diploma Thesis on "Rotation Forest Parallelization". March is a month with several conference deadlines - check the list! Aleck will be spending the next couple of months at IBM Research Zurich.
  • Oct.-Dec. 2016: E. Gallopoulos on sabbatical leave at the Department of CS&E (Computer Science and Engineering) at the University of Minnesota, Minneapolis (picture gallery under continuous update!) Amongst other activities, it was wonderful to meet some HPCLab former members and associates pursuing research careers in the USA (Vasilis Kalantzis, PhD student at the UofM, Eugenia Kontopoulou, PhD student at Purdue and Sophia Sakellaridi, postdoc at Caltech) as well as CEID graduates Kyriakos Ispoglou (PhD student at Purdue), Agi Polyzou (PhD student at the U of Minnesota). During (Thanksgiving) dinner at Professor G. Giannakis' there were even more happy encounters with other CEID alumni who are currently PhD students at the University of Minnesota CS&E Department: In addition to Agi Polyzoy and Vasilis Kalantzis, shown in the picture are Andreas Katis and Nikos Stefas. Also shown is Dimitri Berberidis, former member of the UofP  EECE Dept. and currently PhD student at the UofM ECE. More pictures here.
  • Nov. 2016: E. Gallopoulos attended and presented a talk at the Workshop on Fast Solvers held at Purdue University (picture gallery).
  • Oct. 2016: We are happy to announce that several of our undergraduates have successfully defended their diploma theses and have been admitted to graduate programs at the UofP. Leonidas Kolonias defended his thesis on "Non-negative least squares solvers with multiple right-hand sides and non-negative matrix factorization" and is currently registered at the CEID graduate program. Sofia Tsoni defended her thesis on "A study of the n-gram model and methods for topic extraction and implementation in the TMG environment". Dimitris Christofidellis defended his thesis on "The k-medoids clustering algorithm and variants for parallel processing" (co-supervised by Dr. Venetis) and has started his graduate studies in the interdisciplinary program "Mathematics of Computers and Decision Making". Congratulations to all!
  • Sept. 2016: E. Gallopoulos was plenary speaker at 2016 GAMM Workshop on Applied Numerical Linear Algebra held at TU Hamburg-Harburg. The emphasis of the workshop this year was on "Linear Algebra Challenges in Machine Learning" and EG's talk was on "Clustering, Ranking and Storytelling by Matrices" (group photo and few pictures).
  • Sept. 2016: E. Gallopoulos was invited speaker (talk title "Recent interpretations & implementations of parallel tridiagonal solvers") at the Workshop "Parallel Numerical Computing and Its Applications", in honor of Prof. Mari?n Vajter?ic and organized by the Mathematical Institute of the Department of Informatics of the Slovak Academy of Sciences and held at Smolenice Castle (picture gallery).
  • July 2016: Congratulations to Alex Nakos (former undergraduate at HPCLab) who defended his undergraduate thesis ("Tridiagonal solvers on co-processors: Adapting g-Spike from CUDA to OpenMP for the Intel Xeon Phi manycore") and graduated in July. Alex was offered a scholarship to pursue an MSc in High Performance Computing at the University of Edinburgh (picture).
  • Congratulations to HPCLab (former undergraduate) member Alex Kouris, who was offered a fellowship in order to pursue his PhD at the Department of Electrical and Electronic Engineering at Imperial College. Alex will work under the supervision of Kouris (CEID'98) (together with coauthor and colleague Alex Sobczyk and EG taken during PMAA'14@Lugano).
  • July 2016: HPCLab member Sofia Tsoni was accepted to attend the Undergraduate Summer School on "Learning the Mathematics of Data" of the 2016 PCMI Summer Session, which was held June 30?July 20 at Zermatt Resort in Midway (near Park City), Utah - all travel and living expenses paid by PCMI, which is an outreach program of the School of Mathematics at the Institute for Advanced Study of Princeton. HPCLab had another representative at Park City, Eugenia Kontopoulou who is also a CEID alumnus and soon to be PhD student at Purdue. Congratulations to Sofia and Eugenia! (picture).
  • July 2016: Past and current members of HPCLab (Costas Bekas, Ioannis Venetis, Maria Predari and EG) at the PMAA'16  meeting in Bordeaux. Ioannis Venetis presented the paper "Exploring vectorization possibilities on the Xeon Phi for solving tridiagonal systems", joint work with A. Nakos, Alex Kouris & E. Gallopoulos.
  • March 2016: E. Gallopoulos was invited speaker for a tutorial on "Matrix Computations in Data Analysis" held at the  CRoNoS: Computationally-intensive methods for the robust analysis of non-standard data meeting in Limassol.
  • Jan. 2016: Snapshot of the authors of "Parallelism in Matrix Computations" @ Purdue Memorial Union (21/1/2016).
  • Jan. 2016: See the recent article "RandNLA, Pythons, and the CUR for Your Data Problems: Reporting from G2S3 2015 in Delphi" published in the Jan/Feb issue of SIAM News.
  • Some interesting meetings/conferences/workshops in which we will be active PC participants: PMAA 2016 (Bordeaux), HUCAA'16 (Philadelphia).
  • Dec. 2015:  Bravo for the Silver! Snapshot from the award at Bangalore of HPCLab students (A. Kouris, A. Nakos and N. Nikoloutsakos) for ranking second in the  HiPC 2015 Student Parallel Programming Challenge. The contest was held under the auspices of the IEEE HiPC conference and was supported by Intel and NVIDIA. 
  • Dec. 2015: We salute the publication of the Greek edition of the Golub and Van Loan treatise "Matrix Computations" (4th ed.). It is an important event as this is the first translation of GVL into Greek.
  • Oct. 2015: Congratulations to HPCLab undergraduate students A. Kouris, A. Nakos and graduate student N. Nikoloutsakos, whose clustering code, developed under the supervision of Dr. I. Venetis, was selected for the final round of the HiPC 2015 Student Parallel Programming Challenge.
  • Oct. 2015: Our PARCO submission "A general tridiagonal solver for coprocessors: Adapting g-Spike for the Intel Xeon Phi" was selected for inclusion in the volume of PARCO 2015 papers.
  • Aug. 2015:  "Parallelism in Matrix Computations" by EG, Bernard Philippe and Ahmed Sameh, Springer, Scientific Computation Series, (Sept. 2015) (Brochure, Table of contents, Introduction).
  • Sept. 2015: HPCLab at PARCO'15: Presentation by I. Venetis of joint paper at the conference.
  • June 2015: 2015 Gene Golub SIAM Summer School at Delphi {June 2015)
  • CRoNoS: Computationally-intensive methods for the robust analysis of non-standard data (Brussels COST Management Committee Meeting, March 2015)
  • Professor Yousef Saad visits CEID and the University of Patras (Sept. 2014)
  • Structured Linear and Multilinear Algebra at Kalamata (Sept. 2014)
  • Parallel Matrix Algorithms and Applications (PMAA'14), Lugano (June 2014)
  • NUMAN 2014: Recent approaches in Numerical Analysis, Chania (Sept. 2014)
  • Sabbatical stay at CEID and graduate seminar taught by Professor Steve Vavasis (Spring 2014)