Numerical Algorithms for High-Performance Computational Science Issue of Phil Trans R Soc A

RS journalProfessors Jack Dongarra and Nick Higham, together with Dr Laura Grigori (Inria Paris), have edited the issue Numerical Algorithms for High-Performance Computational Science of the journal Philosophical Transaction of The Royal Society A. The issue is now available online.

The issue contains papers from a Discussion meeting of the same title organized at the Royal Society in April 2019.  A report on that meeting, along with photos from it, is available here.  The content of the issue, with links to the papers, is as follows.

Table of Contents

Numerical algorithms for high-performance computational science by Jack Dongarra, Laura Grigori and Nicholas J. Higham.

The future of computing beyond Moore’s Law by John Shalf.

Hierarchical algorithms on hierarchical architectures by D. E. Keyes , H. Ltaief and G. Turkiyyah.

Stochastic rounding and reduced-precision fixed-point arithmetic for solving neural ordinary differential equations by Michael Hopkins, Mantas Mikaitis, Dave R. Lester and Steve Furber.

Preparing sparse solvers for exascale computing by Hartwig Anzt, Erik Boman, Rob Falgout et al.

On the cost of iterative computations by Erin Carson and Zdeněk Strakoš.

Rethinking arithmetic for deep neural networks by G. A. Constantinides.

Machine learning and big scientific data by Tony Hey , Keith Butler, Sam Jackson and Jeyarajan Thiyagalingam.

The physics of numerical analysis: a climate modelling case study by T. N. Palmer.

Exascale applications: skin in the game by Francis Alexander, Ann Almgren, John Bell et al.

Big telescope, big data: towards exascale with the Square Kilometre Array by A. M. M. Scaife.

Optimal memory-aware backpropagation of deep join networks by Olivier Beaumont, Julien Herrmann, Guillaume Pallez (Aupy) and Alena Shilova.

High-performance sampling of generic determinantal point processes by Jack Poulson.

A survey of algorithms for transforming molecular dynamics data into metadata for in situ analytics based on machine learning methods by Michela Taufer , Trilce Estrada and Travis Johnston.

The parallelism motifs of genomic data analysis by Katherine Yelick , Aydın Buluç, Muaaz Awan et al.

Jack Dongarra Selected to Receive the 2020 IEEE Computer Society’s Computer Pioneer Award

Jack Dongarra

Jack Dongarra

Professor Jack Dongarra, a member of the Manchester Numerical Linear Algebra Group who also holds appointments at the University of Tennessee  and Oak Ridge National Laboratory, has been named as recipient of the IEEE Computer Society’s 2020 Computer Pioneer Award.

The award is given for significant contributions to early concepts and developments in the electronic computer field that have clearly advanced the state-of-the-art in computing.  Dongarra is being recognized “for leadership in the area of high-performance mathematical software.”

Dongarra will receive his award at the Computer Society’s annual awards dinner and presentation to be held on Wednesday 27 May 2020 at the Hilton McLean Tysons Corner during the IEEE Computer Society Board of Governors meeting. The award consists of a silver medal and an invitation to speak at the award presentation.

This article is based on an IEEE news release. Further information about the award is available here.

Poster Successes at SIAM UKIE 2020 Section Meeting

Group photo at SIAM UKIE 2020

Group photo at SIAM UKIE 2020

Several members of the group attended the SIAM UKIE Section Meeting held at the University of Edinburgh on Friday January 10, 2020. Françoise Tisseur, President of the Section and one of the co-organizers, chaired the morning session.

PhD students Michael Connolly,  Xiaobo (Bob) Liu, Gian Maria Negri Porzio, and Research Associate Srikara Pranesh presented posters.

Congratulations to Sri and Michael, who won first and second best poster prizes, respectively:
a cheque for £75 to both and also a copy of the book /50 Visions of Mathematics/ to Sri.

Photo credit to Gian Maria Negri Porzio

 

Issues with Rounding in the GCC Implementation of the ISO 18037:2008 Standard Fixed-Point Arithmetic

Embedded systems are based on low-power, low-performance processors and can be found in various medical devices, smart watches, various communication devices, cars, planes, mobile phones and many other places. These systems come in a hardware and software package optimized for specific computational tasks and most commonly have real-time constraints. As these systems usually have energy usage and cost constraints too, sophisticated numerical hardware that can process floating-point data is not included, but rather only integer arithmetic, which is simpler in terms of area and power of the processors.

ISO 18037:2008 is a standard for embedded C programming language support. It lays out various rules that C compilers should support to make embedded systems easier to program using a high-level language. One of the most important definitions in this standard is fixed-point arithmetic data types and operations. Support for fixed-point arithmetic is highly desirable, since if it is not provided integers with scaling factors have to be used, which makes code hard to maintain and debug and most commonly requires assembler level changes or completely new implementations for each different platform.

The GCC compiler provides some support of the fixed-point arithmetic defined in this standard for ARM processors. However, in my recent technical report (https://arxiv.org/abs/2001.01496) I demonstrated various numerical pitfalls that programmers of embedded systems based on ARM and using GCC can get into. The issues demonstrated include

  • larger than half machine epsilon errors in rounding decimal constants to fixed-point data types,
  • errors in conversions between different data types,
  • incorrect pre-rounding of arguments of mixed-format arithmetic operations before the operation is performed, and
  • lack of rounding of the outputs of arithmetic operations.

These findings can be used to improve the accuracy of various embedded numerical libraries that might be using this compiler. To demonstrate one of the issues, here is a piece of test code:

The multiplication operation is a mixed-format operation, since it multiplies an unsigned long fract argument with an accum argument, therefore it is subject to prerounding of the unsigned long fract argument as described in the report. Since the comparison step in the if () sees that the argument a is larger than zero and b larger than 1, the code is executed with a hope that c will not be set to zero. However, in the arithmetic operation, a is incorrectly pre-rounded to 0, which causes c = 0*b, an unexpected outcome and a bug that is hard to detect and fix.

Numerical Linear Algebra Group Activities 2019

The Numerical Linear Algebra Group had a busy year in 2019. This post summarizes what we got up to. Publications are not included here, but many of them can be found on MIMS EPrints under the category Numerical Analysis; see also these news stories about our publications.

Marcus Webb joined the group in September 2019 as Lecturer in Applied Mathematics.

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Some of the group at the 2019 SIAM Conference on Computational Science and Engineering.

Software

We make our research codes available as open source, principally on GitHub; see the repositories of ConnollyFasiHighamLiuPraneshZounon.

We also put MATLAB software on MATLAB Central File Exchange and on our own web sites, e.g., the Rational Krylov Toolbox (RKToolbox).

PhD Students

Massimiliano Fasi successfully defended his PhD Computing Matrix Functions in Arbitrary Precision Arithmetic in May 2019.

Postdoctoral Research Associates (PDRAs)

Massimiliano Fasi joined us in April 2019 to work with Nick Higham on algorithms for high-performance numerical linear algebra.  He was a Visiting Fellow at the University of Pisa from November 2019 to January 2020.

Mantas Mikaitis joined us in October 2019 on a EPSRC Doctoral Prize Fellowship, having just completed his PhD in the School of Computer Science.

Pierre Blanchard left the group in May 2019 and is now a Numerical Software Engineer at Arm.

Maksims Abalenkovs and Theo Mary left the group in September 2019. Maksims is now a Research Software Engineer with the Science and Technology Facilities Council and Theo is a CNRS researcher at LIP6 in Paris.

Grants

Stefan Güttel, Nick Higham and Françoise Tisseur were awarded a new 30-month KTP project with Arup.  See this news story.

Presentations at Conference and Workshops

Workshop on Scientific Computing and Optimization with Applications to Image and Data Analysis, Hong Kong Baptist University, January 12, 2019: Higham.
Due Giorni di Algebra Lineare Numerica, Sapienza University of Rome, February 18 – 19, 2019: Negri Porzio.
SIAM Conference Computational Science and Engineering (CSE19) in Spokane, USA, February 25 – March 1: Blanchard, Dongarra, Elsworth, Hammarling, Higham, Mary, Pranesh, Tisseur and Zounon.
Liverpool SIAM-IMA Student Chapter Early Career Researcher Conference, University of Liverpool, April 3-5, 2019: Higham.
Royal Society Meeting on Numerical Algorithms for High-Performance Computational Science, April 8 – 9: Blanchard, Fasi, Mary, Pranesh, Zounon.
The 12th International Conference on Numerical Optimization and Numerical Linear Algebra, Shangrao, Jiangxi, China, April 15-18, 2019: Higham.
2nd IMA and OR Society Conference on Mathematics of Operational Research,Birmingham, April 25-26, 2019: Riccietti.
Data-Centric Materials Science and Engineering. Microstructure Fingerprinting and Digital Twinning for Industry 4.0, University of Manchester, May 14-15, 2019: Higham.
Structured Matrix Days, Limoges, France, May 23 – 24, 2019: Mary.
Advances in Numerical Linear Algebra: Celebrating the Centenary of the Birth of James H. Wilkinson, May 29-30,2019: Blanchard, Dongarra, Fasi. Güttel, Hammarling, Higham, Lucas, Tisseur and Zounon. Highlights of the conference.
SIAM UKIE National Student Chapter Conference, University of Manchester, June 10-11, 2019: Fasi.
Gene Golub SIAM Summer School  at the Paul Langevin, Aussois, June 17-28, 2019: Rogers.
Summer School on Optimization, Big Data and Applications (OBA), Veroli, Italy, June 30 – July 6, 2019: Riccietti.
The International Congress on Industrial and Applied Mathematics (ICIAM 2019), Valencia, Spain, July 15-19: Fasi, Güttel, Higham, Pranesh and Tisseur.
International Conference on Continuous Optimization (ICCOPT), Berlin, Germany, August 5-8, 2019: Riccietti.
Franco–German–Swiss (FGS) Conference on Optimization, Nice, France, September 17-20, 2019: Riccietti.
Model Order Reduction Summer School 2019, Academisch Genootschap, Eindhoven, The Netherlands, September 23-27, 2019: Higham.
Computational Science Engineering, Data Science and Artificial Intelligence by Total R&D (MATHIAS), Serris, France, October 14-17, 2019: Riccietti.

Conference and Workshop Organization

ANLA19 group photo

ANLA19 group photo 

IMG_5291.CR2

Vanni Noferini listening to a question from Cleve Moler at ANLA19.

Visitors

Rob Corless from University of Western Ontario visited the group in November 2019.

Recognition and Service

  • Françoise Tisseur delivered the Olga Taussky-Todd Lecture and Nick Higham was an invited speaker at the International Congress on Industrial and Applied Mathematics (ICIAM) in Valencia, Spain, July 2019.
  • Jack Dongarra received the SIAM/ACM Prize in Computational Science and Engineering at the SIAM Conference on Computational Science and Engineering (CSE19)
  • Jack Dongarra was elected as a Foreign Member of the Royal Society.
  • Françoise Tisseur was elected as SIAM UKIE Section President, 2019-20.
  • Steven Elsworth obtained a SIAM Student Travel Award to attend the 2019 SIAM Conference on Computational Science and Engineering (CSE19) in Spokane, Washington.
  • Nick Higham received the London Mathematics Society’s Naylor Prize and Lectureship.
  • Nick Higham delivered the Feng Kang Distinguished Lecture at the Institute of Computational Mathematics and Scientific/Engineering Computing, Chinese Academy of Sciences, Beijing, in April 2019, and the LAA Lecture (formerly the Hans Schneider Lecture) in the Department of Mathematics, University of Wisconsin, Madison, December 2019.

Other Notable Tweets

NLA Group Partnering with Arup on Next Generation Structural Engineering Software

KTP Arup.png

Dr Stefan Güttel, Professor Nick Higham, and Professor Françoise Tisseur have been awarded a new 30-month project with Arup, a multidisciplinary engineering firm operating in all areas of built environment.

This Knowledge Transfer Partnership (KTP), funded by Arup and Innovate UK, aims to embed new matrix eigenvalue solvers into Arup’s next generation software for structural engineering simulation.

The Numerical Linear Algebra  (NLA) group team will be working with Dr Stephen Hendry and Dr Ramaseshan Kannan of Arup, along with a KTP Associate, for which the position is advertised here.

The project builds on a long history of collaboration between Arup and the NLA Group, which has  previously led to the development of “model stability analysis” in Arup’s flagship structural engineering simulation package, Oasys GSA (see the paper What is Your Structural Model Not Telling You?).

Low Precision Floating-Point Formats: The Wild West of Computer Arithmetic

The November 2019 edition of SIAM News contains an article by Research Associate Srikara Pranesh about the growing importance of low precision floating-point arithmetic. Sri describes the opportunities provided by recent hardware and explains how new algorithms are being derived to exploit low precision arithmetic.  To read the article click the image below.

Also see Sri’s recent blog post Simulating Low Precision Floating-Point Arithmetics.

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