# Happy 80th Birthday Cleve!

Today is the 80th birthday of Cleve Moler. Most readers will know Cleve as the inventor of MATLAB. MATLAB was originally a Fortran program that Cleve wrote to give students easier access to the EISPACK and LINPACK libraries. Cleve and John Little later founded The MathWorks and turned MATLAB into a commercial product.

Cleve was a speaker at the conference Advances in Numerical Linear Algebra: Celebrating the Centenary of the Birth of James H. Wilkinson held in Manchester last May. We took the opportunity there to celebrate Cleve’s birthday in advance. A video of Cleve’s talk is included below.

Most recently I saw Cleve at the International Congress on Industrial and Applied Mathematics (ICIAM) conference in Valencia, where he spoke in the minisymposium Bohemian Matrices and Applications that I organized with Rob Corless. See Cleve’s blog post about his talk.

Happy birthday, Cleve!

(Photo credits: Gian Maria Negri Porzio.)

# The Argonne Tapes

A few weeks ago, I was in contact with Chris Paige, an emeritus Professor of Computer Science at McGill University, Montreal. I mentioned that Sven Hammarling and I are collecting information and memorabilia about the numerical analyst James Hardy Wilkinson FRS (1919-1986) for our Wilkinson webpage, and asked Chris if he knew of anything we didn’t already have. He replied “I have 5 1973 Video cassettes, each about 1 hour, by Jim labelled `Eigensystem Workshop June 1973′. … His wonderful lecturing style, and his idiosynchrasies, might be of interest, as well as the marvellous content.”

The tapes contain four talks by Wilkinson and one by Cleve Moler from an Eigensystem Workshop held at Argonne National Laboratory, Illinois, USA, in June 1973.

The tapes are Scotch UC60 High Energy color Videocassettes, in U-matic format, one of which is shown to the right. Chris was able to have the tapes digitized and the results are pretty good given the age of the tapes. We have put the videos on the Numerical Linear Algebra Group YouTube channel and link to them below.

The videos were announced at the recent conference Advances in Numerical Linear Algebra: Celebrating the Centenary of the Birth of James H. Wilkinson, held in Manchester May 29-30, 2019.

• Inverse Iteration – James H. Wilkinson, Eigensystem Workshop, Argonne National Laboratory, Argonne, Illinois, USA, June 1973.

# Joan E. Walsh (1932–2017)

By Len Freeman and Nick Higham

Joan Eileen Walsh was born on 7 October 1932 and passed away on 30 December 2017 at the age of 85.

Joan obtained a First Class B.A. honours degree in Mathematics from the University of Oxford in 1954. She then spent three years working as an Assistant Mistress at Howell’s School in Denbigh, North Wales. In 1957 Joan left teaching and enrolled at the University of Cambridge to study for a Diploma in Numerical Analysis. This qualification was awarded, with Distinction, in 1958. At this point, Joan returned to the University of Oxford Computing Laboratory to study for a D.Phil. under the supervision of Professor Leslie Fox. She was Fox’s first doctoral student. Her D.Phil. was awarded in 1961.

Between October 1960 and March 1963, Joan worked as a Mathematical Programmer for the CEGB (Central Electricity Generating Board) Computing Department in London. In April 1963, she was appointed to a Lectureship in the Department of Mathematics at the University of Manchester. She progressed through the positions of Senior Lecturer (1966) and Reader (1971) before being appointed as Professor of Numerical Analysis at the University of Manchester in October 1974. For the academic year 1967-1968 Joan had leave of absence at the SRC Atlas Computer Laboratory—a joint appointment with St Hilda’s College, Oxford.

Joan led the Numerical Analysis group at the University of Manchester until 1985, after which Christopher Baker took over. This was a period of expansion both for the Numerical Analysis group at Manchester and, more generally, for numerical analysis in Britain. This expansion of British numerical analysis was supported by special grants from the SRC (Science Research Council) to provide additional funding for the subject at the Universities of Dundee, Manchester and Oxford, from 1973 until 1976. This funding supported one Senior Research Fellow and two Research Fellows at each Institution. Joan helped establish the Manchester group as one of the leading Numerical Analysis research centres in the United Kingdom (with eight permanent staff by 1987)—a position that is maintained to the present day.

Joan was Head of the Department of Mathematics between 1986 and 1989, and subsequently became Pro-Vice Chancellor of the University of Manchester in 1990. She held the latter role for four years, and was responsible for undergraduate affairs across the University. Joan’s tenure as Pro-Vice Chancellor coincided with substantial, and sometimes controversial, changes in undergraduate teaching—for example, the introduction of semesterisation and of credit-based degree programmes; Joan managed these major changes across the University with her customary tact, energy and determination. Joan was an efficient and effective administrator at a time when relatively few women occupied senior management roles in universities.

After 35 years’ service, Joan retired from the University in 1998 and was appointed Professor Emeritus.

In retirement, Joan returned to her studies; between 2000 and 2003 she studied for an MA in “Contemporary Theology in the Catholic Tradition” at Heythrop College of the University of London.

Over the years, and particularly during her tenure as Pro-Vice Chancellor, Joan sat on, and chaired, numerous University committees, far too many to list. She had a very long relationship with Allen Hall (a University Hall of Residence) where she was on the Hall Advisory Committee from 1975 until her retirement in 1998.

Joan served leadership roles nationally, as well as in the University. She was Vice President of the IMA (1992-1993) and a member of the Council of the IMA (1990-1991 and 1994-1995). She was elected Fellow of the Institute of Mathematics and its Applications (IMA) in 1984. She was a member of the Computer Board for Universities and Research Councils for several years from the late 1970s. She encouraged the creation of its Software Provision Committee, formally constituted in 1980 with Joan as its first Chairman, which she led until 1985. She was also President of the National Conference of University Professors (1993–1994). Further, she was a member of the Board of Governors at Withington Girls’ School, a leading independent school, for six years between 1993 and 1999.

Nowadays, all computational scientists take for granted the existence of software libraries such as the NAG Library. It is unimaginable to undertake major computational tasks without them. In 1970, Joan was one of a group of four academics who founded the Nottingham Algorithms Group with the aim of developing a comprehensive mathematical software library for use by the group of universities that were running ICL 1906A mainframe computers. Subsequently, the Nottingham Algorithms Group moved from the University of Nottingham to the University of Oxford and the project was incorporated as the Numerical Algorithms Group (NAG) Ltd. Joan became the Founding Chairman of NAG Ltd. in 1976, a position she held for the next ten years. She was subsequently a member of the Council of NAG Ltd. from 1992 until 1996. In recognition of her contribution to the NAG project Joan was elected as a Founding Member of the NAG Life Service Recognition Award in 2011.

Joan’s research interests focused on the numerical solution of ordinary differential equation boundary value problems and the numerical solution of partial differential equations. She conducted much of her research in collaboration with PhD students, supervising the following PhD students at the University of Manchester, who obtained their degrees in the years shown:

• Thomas Sag, 1966;
• Les Graney, 1973;
• David Sayers, 1973;
• Geoffrey McKeown, 1977;
• Roderick Cook, 1978;
• Patricia Hanson, 1979;
• Guy Lonsdale, 1985;
• Chan Basaruddin, 1990;
• Fathalla Rihan (supervised jointly with C. T. H. Baker), 2000.

Joan was an important figure in the development of Numerical Analysis and Scientific Computing at the University of Manchester and in the UK more generally. Her essay Numerical Analysis at the Victoria University of Manchester, 1957-1979 gives an interesting perspective on early developments at Manchester.

Brian Ford OBE, Founder Director of NAG, writes:

Joan had a brilliant career in Mathematics (particularly areas of Numerical Mathematics, Ordinary and Partial Differential Equations), Computing, University Education and Teaching, and was an excellent researcher, teacher, administrator, doctoral supervisor and colleague. But she was so much more than that!

Joan was invariably kind and thoughtful, intellectually gifted and generous with advice and guidance. Her profound Christian faith illuminated every aspect of her life. Joan’s deep reading and wide intellectual interests coupled with her prudence and clear thinking gave her profound knowledge and command. She was excellent company –amusing, modest, never belittling nor intimidating- and enjoyed fine wine and food in good company. She held firm beliefs, gently and persuasively seeking what she saw as the right way. Many people turned to her for help, advice and references and were grateful for her readily-offered help and support.

Joan was a private, even guarded, person. A devout Catholic, on her retirement she completed an MA in “Contemporary Theology in the Catholic Tradition” at Heythorp College, University of London. Fluent in Latin and reading regularly at services, she loved the traditional Tridentine Mass of the Church. Along with her local bishop in Salford and other like-minded Catholics, she therefore worked actively for the restitution of the Tridentine Mass to the liturgy of the world-wide Church (sidelined after Vatican II in favour of local languages), an involvement which culminated her joining high-level discussions at the Vatican. This bore fruit, the Tridentine Latin Mass being officially declared the extraordinary form of the Roman Rite of Mass a few years later: Joan was thrilled. Such was Joan’s commitment to things she believed in and her endless thought and work for others.

Joan was an excellent contributor to the NAG Library, believing strongly in collaboration and sharing, with high quality standards for all aspects of our work and thorough checking and testing. She was an excellent first Chairman of NAG and invaluable colleague and advisor. We thoroughly enjoyed working together, invariably in an excellent spirit. We achieved much.

# Christopher T. H. Baker (1939–2017)

By Nick Higham and Neville Ford (University of Chester)

Christopher Thomas Hale Baker died on August 20, 2017 at the age of 78. He was born on the Isle of Thanet, Kent, in 1939, and was educated at Colchester Royal Grammar School and Jesus College Oxford, where he held an Edwin Jones Scholarship and a State Scholarship.

His first full-time employment was between school and college, when he worked in the Physics Research Laboratory of BX Plastics. He obtained his BA in 1961 and his M.A. and D.Phil., in 1964, from the University of Oxford. Between 1964 and 1966 he held a Fulbright Award and was Instructor and PG Research Mathematician at UC Berkeley. From 1966 Christopher was lecturer, senior lecturer and then reader at the University of Manchester, becoming professor in 1989. He had periods of leave at the University of Toronto (in 1972 and 1976) and Oxford University.

Christopher served as head of the numerical analysis group for around ten years and served as Head of Department for three years from September 1995. Following his retirement in 2004, Christopher joined the University of Chester as a part-time member of the department, retiring from that role in 2016. At the time of his death he held the title of Emeritus Professor at both the University of Manchester and the University of Chester.

Christopher was founding Director of the Manchester Centre for Computational Mathematics (MCCM), formed in 1992 by the numerical analysis groups at the University of Manchester and UMIST to build on existing collaborations. In his ten years as Director, the centre grew substantially in activity, as seen particularly in the Numerical Analysis Report series, and the M.Sc. in Numerical Analysis and Computing. Christopher was instrumental in involving external researchers in MCCM, notably the Chester numerical analysts.

His research interests included numerical solution of integral equations and functional differential equations (integro-differential and delay-differential equations), and parameter estimation in models. He is perhaps best-known for his monumental 1034-page monograph Numerical Treatment of Integral Equations (Clarendon Press, Oxford, 1977). He was able to expand some of the tools and techniques developed for integral equations into newly emerging fields of numerical dynamics and numerical methods for stochastic differential equations.

Christopher organized two Durham Symposia. The first, “Numerical Treatment of Integral Equations” (1982), was attended by 67 mathematicians from around the world. The second, “Evolutionary Problems: Continuous and Discretized Nonlinear Systems” (July 4-14, 1992), organized jointly with Ruth Thomas, had 92 attendees.

In his introduction to the 2000 annual report of MCCM, Christopher offered some thoughts on the nature of Numerical Analysis.

“To some, the emphasis should be on computational mathematics, to others the emphasis should be on a unifying perspective from the viewpoint of applied analysis. To the writer, numerical analysis is ideally a broad church and like other sections of applied mathematics should be informed by modelling considerations, investigations based on simulation or analysis, and the practicalities of modern computing. As an integrated part of applied mathematics, the skills developed in numerical analysis complement and are complemented by perspectives obtained from other areas; numerical analysis should be supported by insights from modelling, and from the more abstract areas of mathematics, and computer science.”

Those words strike us as just as valid today as when Christopher wrote them seventeen years ago.

Christopher was a member of the 1992 Mathematics Assessment Panel in the UFC Research Assessment Exercise and of the Applied Mathematics panel in the 1996 Research Assessment Exercise. He chaired the Applied Mathematics panel in the 2001 Research Assessment Exercise. Serving on three successive panels was a major service to the mathematics community. Some idea of this is given by Christopher’s comment in the 2002 MCCM annual report, “During most of 2001, every flat surface at home and in my office was covered with RAE paperwork”.

He was a Fellow of the Institute of Mathematics and its Applications and served as editor of the IMA Journal of Numerical Analysis from its foundation in 1981 to 1996. He was a dedicated editor, also giving long service to other journals including Journal of Computational and Applied Mathematics, Journal of Integral Equations and Applications, and Advances in Computational Mathematics.

Here is a list of his PhD students (complete as far as we know), with their last known affiliations.

• Ian Gladwell (Southern Methodist University, Dallas)
• Malcolm Keech (University of Bedfordshire)
• Siamak Amini (University of Salford)
• Athena Makroglou (University of Portsmouth)
• Mishi Derakshan (Dassault Systems BIOVIA)
• Neville Ford (University of Chester)
• Christopher Paul (University of Manchester)
• David Willé (Heidelberg, Germany)
• Arsalang Tang (Concordia University, Montreal, Canada)
• Fathalla A. Rihan (United Arab Emirates University)
• Ali Filiz (Adnan Menderes University, Turkey)
• Hongjiong Tian (Shanghai Normal University, China)
• Yihong Song (Suzhou University, Jiangsu, China)
• Ephraim O. Agyingi (Rochester Institute of Technology, NY)
• Eugene Parmuzin (INMRAS, Moscow, Russia)

Christopher had heart bypass surgery in 1988 and the surgeon told him “We know these vein grafts last for 12 years”. Thankfully, that was a severe underestimate, and Christopher maintained all his usual activities right until the end.

Christopher will be remembered as a kind, generous, and sociable colleague as well as for his leadership in applied mathematics and numerical analysis in Manchester, Chester, across the UK, and beyond.

Christopher is survived by his wife Helen, his children Deborah and Mark, and four grandchildren

Nick writes:

Christopher was a student at Oxford when Leslie Fox was Professor of Numerical Analysis and head of the Computing Laboratory. According to David Sayers, Fox used to refer to Christopher as “that pure mathematician”—presumably because of the rigorous mathematical approach that Christopher used in his research on the numerical treatment of integral equations. When I was a PhD student I remember hearing of a seminar where the speaker showed how to solve numerically an integral equation for which there was later shown to be no solution. Christopher would never fall into such a trap! He served for three years on the adjudicating committee for the Leslie Fox prize, chairing it in 1997. He dedicated a paper (“Parallel continuous Runge-Kutta methods and vanishing lag delay differential equations”, 1993) to the memory of Leslie Fox.

Christopher was a shrewd operator at faculty level. He secured many promotions in the department at a time when they were limited by university finances. He was responsible for mathematics being chosen as the location for a large PC cluster in the early days of the use of PCs for teaching. I found a 1993 email in which Christopher wrote, to colleagues in the department, many of whom were not au fait with computing:

“You may ask why it is thought that computers can assist teaching … Computers can be used to yield visual and numerical insight, if the right packages are used. They can also access databases (library catalogues, journal and book reviews, etc.) The international trends are quite clear. It is also quite clear that computers are a genuine aid to modern mathematical research and development; some of our graduates will become real mathematicians.”

Christopher was an enthusiastic early adopter of email, originally on the university CMS system. He was professor in charge of computing for many years in the 1990s: a major task in a time of rapid change.

Neville writes:

Christopher’s involvement with colleagues at the University of Chester stems from his collaboration with me that has lasted more than 30 years. My former pure mathematics tutor, Brian Steer (who had been a student with Christopher during his time at Jesus College) put me in touch with Christopher as somebody who could supervise me (interests in functional and classical analysis) and help me establish myself in numerical analysis. As Nick describes, Christopher was always shrewd. I recognise the way careful supervision encouraged students to play to their strengths and to answer research questions which other people would find to be interesting. He frequently reminded us all that no question is worth answering unless somebody other than the author of the paper is asking it. I also remember being challenged repeatedly by his question ‘what do you mean by …’ (stability, for example) reflecting his determination to understand the underlying mathematics before venturing an opinion on a numerical scheme.

Christopher was responsible for inviting members of the Chester mathematics team to join with the Manchester Centre for Computational Mathematics, a co-operation which worked very effectively for our emerging research group, and on his retirement from Manchester we were pleased to welcome him as a member of our team, so collaborations between Christopher and the Chester group continued to develop. Even though some new members of our group had known him only for a short time before his death, they describe how much he continued to help by challenging their thinking, suggesting interesting fresh insights and contributing to the seminar programme.

Updated October 4, 2017 to correct the list of PhD students.

# Celebrating Charlie Van Loan

Charlie Van Loan, Joseph C. Ford Professor of Engineering in the Department of Computer Science at Cornell University, retires in summer 2016.

Charlie has been a huge inspiration to me and many others, not least through his book Matrix Computations, with Gene Golub, now in its fourth edition. I wrote about the book on the occasion of the publication of the fourth edition (2013) in this previous post.

Following his PhD at the University of Michigan, Charlie visited the Department of Mathematics at the University of Manchester in 1974–1975 as a Science Research Council Research Fellow. He wrote the department’s first Numerical Analysis Report as well as three more of the first ten reports, as explained in this post.

A 55-minute video interview with Charlie by his colleague Kavita Bala, recorded in 2015, is available at the Cornell University eCommons. In it, Charlie talks about his PhD, with Cleve Moler as advisor, life as a young Cornell faculty member, the “GVL” book, computer science education, and many other things.

A two-part minisymposium is being held in Charlie’s honor at the SIAM Annual Meeting in Boston, July 11-14, 2016, organized by David Bindel (Cornell University) and Ilse Ipsen (North Carolina State University). I will be speaking in the second part about Charlie’s work on the matrix exponential. The details are below. If you will be at the meeting come and join us. I hope to provides links to the slides after the event.

SIAM Annual Meeting 2016.
Numerical Linear and Multilinear Algebra: Celebrating Charlie Van Loan.
Wednesday, July 13

Part I: MS73, MS89: 10:30 AM – 12:30 PM. BCEC Room 254B. Abstracts

• 10:30-10:55 Parallel Tucker-Based Compression for Regular Grid Data, Tamara G. Kolda, Sandia National Laboratories, USA
• 11:00-11:25 Cancer Diagnostics and Prognostics from Comparative Spectral Decompositions of Patient-Matched Genomic Profiles, Orly Alter, University of Utah, USA
• 11:30-11:55 Exploiting Structure in the Simulation of Super Carbon Nanotubes, Christian H. Bischof, Technische Universität Darmstadt, Germany
• 12:00-12:25 A Revisit to the GEMM-Based Level 3 BLAS and Its Impact on High Performance Matrix Computations abstract Bo T. Kågström, Umeå University, Sweden

Part II: MS92, 4:00 PM – 6:00 PM. BCEC Room 254B. Abstracts

• 4:00-4:25 Charlie Van Loan and the Matrix Exponential, Nicholas J. Higham, University of Manchester, United Kingdom
• 4:30-4:55 Nineteen Dubious Ways to Compute the Zeros of a Polynomial, Cleve Moler, The MathWorks, Inc., USA
• 5:00-5:25 The Efficient Computation of Dense Derivative Matrices in MATLAB Using ADMAT and Why Sparse Linear Solvers Can Help, Thomas F. Coleman, University of Waterloo, Canada
• 5:30-5:55 On Rank-One Perturbations of a Rotation, Robert Schreiber, Hewlett-Packard Laboratories, USA

# Jeff Rohl’s Fortran TV Course

As a first year mathematics undergraduate at the University of Manchester in 1979, I had to choose one course from another department. Like the majority of students, I chose the Fortran Programming course CS151 provided for mathematics students by the Department of Computer Science.

The course tutor was Simon Lavington, who is now perhaps best known for his historical research into early British computers (and can be seen on this video about the Ferranti Atlas computer). It used a videotaped set of lectures by Jeff Rohl. Jeff was an Australian who had come to Manchester in 1960 to do a PhD on compilers with Tony Brooker. He became a Professor at UMIST in the early 1970s and returned to Australia in 1976 to found the Department of Computer Science at the University of Western Australia.

 Jeff Rohl

The ten black and white videos, Programming in Fortran (1973), were accompanied by a 124-page book of the same title, written by Jeff and published by the University of Manchester Press.

These were the early days of computing. The book talked about punched cards, which thankfully we students did not have to use, and employed flowcharts (which it called “flow diagrams”) to illustrate the logical flow of programs. The book included the complete Fortran 66 standard in an appendix—something that would be inconceivable with most languages of today!

Many years later I met Jeff while we were both visiting the Computer Science Department at Cornell University. He said that people regularly tell him that they learned Fortran from his book and lectures and that the videos were recorded in one continuous take. In this YouTube era it is easy to forget how innovative these early 1970s video lectures were.

Fortran is of course still around and has a large user community. Indeed it ranks 24th in the January 2016 version of the TIOBE Programming Community Index. For some context on its usage see my article Programming Languages: An Applied Mathematics View in The Princeton Companion to Applied Mathematics.

The most recent standard is Fortran 2008 and another revision is in preparation. An old joke goes “I don’t know what language we’ll be using in 50 years time, but it will be called Fortran.”

I was sorry to discover that Jeff passed away in 2003.

Simon Lavington has kindly provided me with more information about the TV lecture courses—three in total—recorded by him and Jeff Rohl in the Department of Computer Science. I will write about these in a subsequent post.

I am grateful to Jeff’s son Andrew Rohl for providing the photo of Jeff above.

# Jack Williams (1943–2015)

Jack Williams passed away on November 13th, 2015, at the age of 72.

Jack obtained his PhD from the University of Oxford Computing Laboratory in 1968 and spent two years as a Lecturer in Mathematics at the University of Western Australia in Perth. He was appointed Lecturer in Numerical Analysis at the University of Manchester in 1971.

He was a member of the Numerical Analysis Group (along with Christopher Baker, Ian Gladwell, Len Freeman, George Hall, Will McLewin, and Joan Walsh) that, together with numerical analysis colleagues at UMIST, took the subject forward at Manchester from the 1970s onwards.

Jack’s main research area was approximation theory, focusing particularly on Chebyshev approximation of real and complex functions. He also worked on stiff ordinary differential equations (ODEs). His early work on Chebyshev approximation in the complex plane by polynomials and rationals was particularly influential and is among his most-cited. Example contributions are

J. Williams (1972). Numerical Chebyshev approximation by interpolating rationals. Math. Comp., 26(117), 199–206.

S. Ellacott and J. Williams (1976). Rational Chebyshev approximation in the complex plane. SIAM J. Numer. Anal., 13(3), 310–323.

His later work on discrete Chebyshev approximation was of particular interest to me as it involved linear systems with Chebyshev-Vandermonde coefficient matrices, which I, and a number of other people, worked on a few years later:

M. Almacany, C. B. Dunham and J. Williams (1984). Discrete Chebyshev approximation by interpolating rationals. IMA J. Numer. Anal. 4, 467–477.

On the differential equations side, Jack wrote the opening chapter “Introduction to discrete variable methods” of the proceedings of a summer school organized jointly by the University of Liverpool and the University of Manchester in 1975 and published in G. Hall and J. M. Watt, eds, Modern Numerical Methods for Ordinary Differential Equations, Oxford University Press, 1976. This book’s timely account of the state of the art, covering stiff and nonstiff problems, boundary value problems, delay-differential equations, and integral equations, was very influential, as indicted by its 549 citations on Google Scholar. Jack contributed articles on ODEs and PDEs to three later Liverpool–Manchester volumes (1979, 1981, 1986).

Jack’s interests in approximation theory and differential equations were combined in his later work on parameter estimation in ODEs, where a theory of Chebyshev approximation applied to solutions of parameter-dependent ODEs was established, as exemplified by

J. Williams and Z. Kalogiratou (1993). Least squares and Chebyshev fitting for parameter estimation in ODEs. Adv. Comp. Math., 1(3), 357–366.

More details on Jack’s publications can be found at his MathSciNet author profile (subscription required). Some of his later unpublished technical reports from the 1990s can be accessed at from the list of Numerical Analysis Reports of the Manchester Centre for Computational Mathematics.

Jack spent a sabbatical year in the Department of Computer Science at the University of Toronto, 1976–1977, at the invitation of Professor Tom Hull. Over a number of years several visits between Manchester and Toronto were made in both directions by numerical analysts in the two departments.

It’s a fact of academic life that seminars can be boring and even impenetrable. Jack could always be relied on to ask insightful questions, whatever the topic, thereby improving the experience of everyone in the room.

Jack was an excellent lecturer, who taught at all levels from first year undergraduate through to Masters courses. He was confident, polished, and entertaining, and always took care to emphasize practicalities along with the theory. He had the charisma—and the loud voice!—to keep the attention of any audience, no matter how large it might be.

He studied Spanish at the Instituto Cervantes in Manchester, gaining an A-level in 1989 and a Diploma Basico de Espanol Como Lengua Extranjera from the Spanish Ministerio de Educación y Ciencia in 1992. He subsequently set up a four-year degree in Mathematics with Spanish, linking Manchester with Universidad Complutense de Madrid.

Jack was promoted to Senior Lecturer in 1996 and took early retirement in 2000. He continued teaching in the department right up until the end of the 2014/2015 academic year.

I benefited greatly from Jack’s advice and support both as a postgraduate student and when I began as a lecturer. My office was next to his, and from time to time I would hear strains of classical guitar, which he studied seriously and sometimes practiced during the day. For many years I shared pots of tea with him in the Senior Common Room at the refectory, where a group of mathematics colleagues met for lunchtime discussions.

Jack was gregarious, ever cheerful, and a good friend to many of his colleagues. He will be sadly missed.

# Michael J. D. Powell (1936–2015)

I would like to share a couple of photos of Mike Powell, FRS, who passed away last month. The photos are from early and late in his career.

The first is one of a set of contact prints from a role of Kodak black and white film that I came across in a collection of photos belonging to Gene Golub, which I was able to look through after Gene’s death in 2007. It is clear from the complete set of images that they were taken in or around the Courant Institute. The photos are undated, but Olof Widlund (who appears in some of them) tells me that the photos are most likely from 1965-1966.

The second image is from June 2013 and was taken at the banquet at the Biennial Conference in Numerical Analysis at the University of Strathclyde. Mike is flanked on his right by Iain Duff and on his left by Juan Meza. Mike was a regular attendee at this conference and starting at next month’s conference there will be a regular Fletcher-Powell Invited Lecture, honouring Roger Fletcher and Mike Powell’s contributions to numerical analysis and, particularly, nonlinear optimization.

A memorial web site for Mike has been set up.

# Hans Schneider (1927–2014)

I first met Hans in 1984 at the Gatlinburg meeting IX in Waterloo, Canada, at which time I was a PhD student. When I discussed my work on matrix square roots with him he recalled a 1966 paper by Culver “On the Existence and Uniqueness of the Real Logarithm of a Matrix”, of which I was unaware. By the time I returned to Manchester, after visiting Stanford for a few weeks, a copy of the paper was waiting for me, with an explanation of how the results of that paper could be adapted to analyze real square roots of a real matrix.

As chair of the 2002 Householder symposium XV in Peebles, Scotland, I was delighted to invite Hans to deliver the after-dinner speech. (The Gatlinburg meeting was renamed the Householder symposium in 1990, in honour of Alston Householder, who organized the early meetings.) Having Hans speak was particularly appropriate as he had studied at the nearby University of Edinburgh. I believe this was the last Householder Symposium that Hans attended.

I kept a copy of my introduction of Hans at the banquet. It seems appropriate to reproduce it here.

Ladies and gentlemen, our after-dinner speaker this evening is Hans Schneider, who is James Joseph Sylvester Emeritus Professor of Mathematics at the University of Wisconsin.

There’s an old definition that an intellectual is somebody who can hear the William Tell overture and not think of the Lone Ranger. I don’t think there are many people who can hear the term “linear algebra and its applications” and not think of Hans Schneider. After all, Hans has been Editor-in-Chief of the journal of that name since 1972, and developed it into a major mathematics journal. Hans was also instrumental in the foundation of the International Linear Algebra Society, of which he served as President from 1987 to 1996.

Some of you may be surprised to know that Hans has a strong connection with Scotland. He studied here and received his Ph.D. at Edinburgh University in 1952 under the famous Alexander Craig Aitken. I understand that Aitken gave him two words of advice: “Read Frobenius!”.

Well, it’s a real pleasure to introduce Hans and to ask him to speak on “The Debt Linear Algebra Owes Helmut Wielandt”.

The reference to Frobenius is apposite, given my original conversation with Hans since, as I have only recently discovered, Frobenius gave one of the earliest proofs of the existence of matrix square roots in 1896. That result, and much more about Frobenius’s wide range of contributions to mathematics is discussed in a 2013 book by Thomas Hawkins, The Mathematics of Frobenius in Context. A Journey Through 18th to 20th Century Mathematics (of which my copy has the rare error of having the odd pages on the left, rather than the right, of each two-page spread).

The photo below was taken during Hans’s after-dinner speech (more photos from the meeting are available in this gallery).

# The Life of James Joseph Sylvester

Following my previous post about the James Joseph Sylvester Bicentenary and my article Sylvester’s Influence on Applied Mathematics I now give a brief, very selective, overview of Sylvester’s life. Some of this material was used in an after-dinner speech that I gave at the Householder Symposium XIX on Numerical Linear Algebra at Spa, Belgium on June 11, 2014.

I’ve drawn on many sources for this post, but the most important is the 2006 biography by Karen Parshall, James Joseph Sylvester. Jewish Mathematician in a Victorian World. That title brings out two key points: that Sylvester was Jewish, which hindered his career, as we will see, and that he lived much of his life in Victorian England, when almost everything that today we take for granted when doing our research did not exist.

## Thumbnail Sketch of The Man

Sylvester was born in London in 1814. He was short, mercurial, absent-minded, temperamental, fluent in French, German, Italian, Latin and Greek, and loved poetry but was not very good at it. He was a man of remarkable tenacity, as his career on both sides of the Atlantic shows.

## Career Outline

I’ll give a brief outline of Sylvester’s unusual career, with its many ups and downs, then go on to discuss some specific events in his life.

### First Spell in UK

• Sylvester was a student at University College London (UCL) under De Morgan, age 14. He was withdrawn by his family after attempting to stab a fellow pupil.
• He was a student at Cambridge, but was not able to take the degree because he was Jewish.
• He held the chair of natural philosophy at University College London (UCL) for three years.

### First Sojourn in USA

Sylvester became Professor of Mathematics at the University of Virginia in 1841. He left after four months after an altercation with an unruly student, because he was felt that the faculty did not back him up in a subsequent inquiry.

While in New York he applied for a position at Columbia University. According to R. L. Cooke (quoted in James Joseph Sylvester. Life and Work in Letters)

After leaving Virginia he sought a position at Columbia University, with a recommendation from one of America’s leading scientists, Joseph Henry. In a wonderful irony … the selection committee informed him that his rejection was in no way connected with the fact that he was British, only the fact that he was Jewish.

### Rest of Career (age 29–).

• Sylvester Worked for the next decade as an actuary for the Equity and Law Life Assurance Society in London and trained for the Bar. He founded the Institute of Actuaries. This is when he met Cayley, who became his best friend. For this ten-year period he was doing mathematics in his spare time.
• He was appointed Chair at the Royal Military Academy, Woolwich and spent 15 years there.
• He was appointed Chair at the newly founded Johns Hopkins University, Baltimore, at the age of 61. He negotiated a salary of \$5000 payable in gold, plus an annual housing allowance of \$1000 also payable in gold.
• His final position was as the Savilian Professor of Geometry at New College, Oxford in 1883, which he took up at the age of 69.

## The Neologist

Sylvester introduced many terms that are still in use today, including matrix (1850), canonical form (1851), Hessian (1851), and Jacobian (1852). Another notable example is the term latent root, which Sylvester introduced in 1883, with two charming similes:

“It will be convenient to introduce here a notion (which plays a conspicuous part in my new theory of multiple algebra), namely that of the latent roots of a matrix—latent in a somewhat similar sense as vapour may be said to be latent in water or smoke in a tobacco-leaf.”

The term has fallen out of use in linear algebra and matrix theory, but it can still be found in use through “the latent root criterion” in, for example (to pick two articles found with a Google search) Differentiating with brand personality in economy hotel segment in Journal of Vacation Marketing (2014) and GHOSTS: A travel barrier to tourism recovery in Annals of tourism research (2011).

## Editor

Sylvester did a great deal of editorial work. He was an editor of the Quarterly Journal of Mathematics for 23 years. He founded the American Journal of Mathematics in 1878 when he was at Johns Hopkins University. This was the first mathematics research journal in the USA, and indeed Sylvester set up the first mathematics research department in the country. As Editor-in-Chief he experienced some of the problems that subsequent journal editors have suffered from.

• He had to work very hard to secure high quality contributions, e.g., from his friend Cayley and from students and colleagues at Johns Hopkins, in addition to his own papers.
• He solicited Alfred Kempe’s proof of the four color theorem. After Sylvester had accepted the paper his managing editor, William Story, realized there was a gap in the reasoning, due to overlooked cases, and wrote a note the accompany the paper in which he unsuccessfully tried to patch the proof. This all happened while Sylvester was in England and he was very unhappy with the incident.

## Author

Even though Sylvester was an editor himself, he was also the author from hell! He was notorious for what his biographer Parshall calls “an impatience with bibliographic research”—something that led him into disputes with other mathematicians.

MacFarlane states that

Sylvester never wrote a paper without foot-notes, appendices, supplements; and the alterations and corrections in his proofs were such that the printers found their task well-nigh impossible. … Sylvester read only what had an immediate bearing on his own researches, and did little, if any, work as a referee.

The title of one particular paper illustrates this point:

J. J. Sylvester, Explanation of the Coincidence of a Theorem Given by Mr
Sylvester in the December Number of This Journal, With One Stated by
Professor Donkin in the June Number of the Same, Philosophical Magazine
(Fourth Series) 1, 44-46, 1851

## Secular Equation Paper

Out of Sylvester’s hundreds of papers, one in particular stands out as notable to me: “On the Equation to the Secular Inequalities in the Planetary Theory”, Philosophical Magazine 16, 267-269, 1883, for the following reasons.

• The title has virtually nothing to do with the paper.
• This is the paper in which Sylvester defines the term latent roots—but as if a totally new concept, even though the concept of matrix eigenvalue was already known.
• He states a theorem about a sum of products of latent roots of a product $AB$ being expressible in terms of sums of products of minors of $A$ and $B$.
• He gives the first general definition of function of a matrix (later refined by Buchheim).
• He discusses the special case of $p$th roots.

The paper is short (3 pages), no proper introduction is given to these concepts, and no proofs are given. In short, a brilliant but infuriating paper!

## Baltimore Summer

In these days of ubiquitous air conditioning it is interesting to note one of the things that made it difficult for Sylvester to do research. Parshall writes, of Sylvester in Baltimore,

“He could not concentrate on his research on matrices in the debilitating summer heat and humidity”.

## Teaching

Sylvester’s enthusiasm for matrices is illustrated by his attempt to teach the theory of substitutions out of a new book by Netto. Sylvester

“lectured about three times, following the text closely and stopping sharp at the end of the hour. Then he began to think about matrices again. `I must give one lecture a week on those,’ he said. He could not confine himself to the hour, nor to the one lecture a week. Two weeks were passed, and Netto was forgotten entirely and never mentioned again.” (Parshall, p. 271, quoting Ellery W. Davis).

Compare this with the following quote about E. T. Bell (famous for his book Men of Mathematics, 1937), from Constance Reid’s book about Bell:

Bell’s method of teaching was to read a sentence aloud and announce that he didn’t believe it. `By the time we students convinced him that it was true,’ concedes Highberg, `we pretty well understood it ourselves.’

## Inaugural Lecture at Oxford, 12 December 1885

There are many ways in which we are more fortunate today than mathematicians of Sylvester’s time. But there were some advantages to those times. From his inaugural lecture, published as On the Method of Reciprocants as Containing an Exhaustive Theory of the Singularities of Curves (Nature, 1886)

It is now two years and seven days since a message by the Atlantic cable containing the single word “elected” reached me in Baltimore informing me that I had been appointed Savilian Professor of Geometry in Oxford, so that for three weeks I was in the unique position of filling the post and drawing the pay of Professor of Mathematics in each of two Universities:

## Obstinacy

Emile Picard recounted how Sylvester, on a visit to Paris, asked him if in six weeks he could learn the theory of elliptic functions. Picard said yes, so Sylvester asked if a young geometer could be assigned to give him lessons several times per week. This began, but from the second lesson reciprocants and matrices started to compete with elliptic functions and in the ensuing several lessons Sylvester taught the young geometer about his latest research and they remained on that topic.

## What Can We Learn from Sylvester’s Life?

If I had to draw two pieces of advice from Sylvester’s life story I would choose the following.

• You are never too old to take on a major challenge (he took up the chair at Johns Hopkins University at the age of 61).
• If you want to be remembered, define some new terms and have some theorems named after you!