Numerical LinearMatters Algebra in the UK: Research From Cayley to Exascale Computing February 25, 2009 Nick Higham Nick Higham SchoolofofResearch Mathematics Director The University of Manchester School of Mathematics higham@ma.man.ac.uk http://www.ma.man.ac.uk/~higham/ ENUMATH Conference 2011 September 5–9, 2011 Leicester 1/6 Outline MIMS 1 Matrices 2 Applications 3 History 4 Machines and Computation 5 Towards Exascale Nick Higham Linear Algebra in the UK 2 / 53 What is a Matrix? Matrix = array = table of numbers. E.g. −4 −11 3 −6 −17 12 2 22 1 12 −2 −1 3 0 7 1 . Penguin Dictionary of Mathematics (4th ed., 2008): A set of quantities arranged in a rectangular array, with certain rules governing their combination. Term “matrix” coined in 1850 by James Joseph Sylvester, FRS (1814–1897). MIMS Nick Higham Linear Algebra in the UK 3 / 53 Correlation Matrix An n × n matrix A for which aij is the correlation between variables i and j. E.g. 1.00 −0.28 0.75 −0.09 −0.28 1.00 0.25 −0.53 . 0.75 0.25 1.00 −0.08 −0.09 −0.53 −0.08 1.00 Some properties: symmetric, 1s on the diagonal, off-diagonal elements between −1 and 1. MIMS Nick Higham Linear Algebra in the UK 4 / 53 Correlation Matrix An n × n matrix A for which aij is the correlation between variables i and j. E.g. 1.00 −0.28 0.75 −0.09 −0.28 1.00 0.25 −0.53 . 0.75 0.25 1.00 −0.08 −0.09 −0.53 −0.08 1.00 Some properties: symmetric, 1s on the diagonal, off-diagonal elements between −1 and 1. MIMS Nick Higham Linear Algebra in the UK 4 / 53 Leslie Matrix Model for growth of female portion of an animal population; P. H. Leslie (1945). Model with 4 age classes: 0 9 12 6 1/3 0 0 0 . L= 0 1/2 0 0 0 0 1/4 0 Row 1: average births per age class. Subdiagonal: survival rates from one age class to next. MIMS Nick Higham Linear Algebra in the UK 5 / 53 Magic Square Dürer’s Melencolia I (1514) MIMS Nick Higham Linear Algebra in the UK 6 / 53 Magic Square MIMS Nick Higham Linear Algebra in the UK 6 / 53 Matrix (1) Consider set of all Web pages on the internet. Define gij = 1 if page i links to page j: 1 2 3 4 1 0 1 1 0 2 1 0 1 0 . 3 0 1 1 1 4 0 0 1 0 Then scale rows so they sum to 1 (stochastic matrix): 1 2 3 1 0 1/2 1/2 2 1/2 0 1/2 3 0 1/3 1/3 4 0 0 1 MIMS Nick Higham 4 0 0 . 1/3 0 Linear Algebra in the UK 7 / 53 Matrix (2) Google matrix for http://www.manchester.ac.uk: MIMS Nick Higham Linear Algebra in the UK 8 / 53 Popularity Number of hits from Google search on exact phrase: Correlation Matrix Magic Square Leslie Matrix Google Matrix MIMS Nick Higham 2011 2007 1,030,000 702,000 915,000 418,000 35,900 37,600 46,000 928 Linear Algebra in the UK 9 / 53 Outline MIMS 1 Matrices 2 Applications 3 History 4 Machines and Computation 5 Towards Exascale Nick Higham Linear Algebra in the UK 10 / 53 “Matrices offer some of the most powerful techniques in modern mathematics. In the social sciences they provide fresh insights into an astonishing variety of topics.” Penguin, 1986. Chapter 4: Matrices and Matrimony in Tribal Societies. Alan Turing Building Panorama MIMS Nick Higham Linear Algebra in the UK 12 / 53 Alan Turing Building Panorama MIMS Nick Higham Linear Algebra in the UK 12 / 53 Alan Turing Building Panorama MIMS Nick Higham Linear Algebra in the UK 12 / 53 Alan Turing Building Panorama Nonlinear least squares, Levenberg–Marquardt: (J T J + λD)d = J T r , MIMS Nick Higham J ∈ R3200×32 for 8 images. Linear Algebra in the UK 12 / 53 Jpeg Image Format Jpeg compression first converts from RGB to YCb Cr colour space where Y = luminance, Cb , Cr = blue, red chrominances, by Y 0.299 0.587 0.114 R Cb = −0.1687 −0.3313 0.5 G . Cr 0.5 −0.4187 −0.0813 B Vision has poor response to spatial detail in coloured areas of same luminance ⇒ Cb , Cr can take greater compression. MIMS Nick Higham Linear Algebra in the UK 13 / 53 Outline MIMS 1 Matrices 2 Applications 3 History 4 Machines and Computation 5 Towards Exascale Nick Higham Linear Algebra in the UK 14 / 53 Linear System Jiu Zhang Suanshu (Nine Chapters of the Mathematical Art), around 1 AD. T /M/L = sheaves of rice stalks from top/medium/low grade paddies. Find yield (in dou) for each quality of sheaf, given overall yields as follows: 3T + 2M + L = 39, 2T + 3M + L = 34, T + 2M + 3L = 26. MIMS Nick Higham Linear Algebra in the UK 15 / 53 Cayley and Sylvester Term “matrix” coined in 1850 by James Joseph Sylvester, FRS (1814–1897). Matrix algebra developed by Arthur Cayley, FRS (1821– 1895). Memoir on the Theory of Matrices (1858). MIMS Nick Higham Linear Algebra in the UK 16 / 53 Cayley Sylvester Enter Cambridge University Wrangler in Tripos examinations Work in London Trinity College, 1838 Senior Wrangler, 1842 Pupil barrister from 1846; called to the Bar in 1849 St. John’s College, 1831 Second wrangler, 1837 Elected Fellow of the Royal Society President of the London Mathematical Society Awarded Royal Society Copley Medal Awarded LMS De Morgan Medal British Assoc. for the Advancement of Science 1852 Actuary from 1844; pupil barrister from 1846; called to the Bar in 1850 1839 1868–1869 1866–1867 1882 1880 1884 1887 President, 1883 Vice President, 1863–1865; President of Section A, 1869 Academic Positions Cayley Sylvester • Sadleirian Chair, Cambridge 1863 • UCL, 1838 • U Virginia, 1841 • Royal Military Academy, Woolwich, London, 1855 • Johns Hopkins University 1876 • Savilian Chair of Geometry, Oxford, 1883 MIMS Nick Higham Linear Algebra in the UK 18 / 53 Biographies Tony Crilly, Arthur Cayley: Mathematician Laureate of the Victorian Age, 2006. Karen Hunger Parshall, James Joseph Sylvester. Jewish Mathematician in a Victorian World, 2006. MIMS Nick Higham Linear Algebra in the UK 19 / 53 Matrices in Applied Mathematics Frazer, Duncan & Collar, Aerodynamics Division of NPL: aircraft flutter, matrix structural analysis. Elementary Matrices & Some Applications to Dynamics and Differential Equations, 1938. Emphasizes importance of eA . Arthur Roderick Collar, FRS (1908–1986): “First book to treat matrices as a branch of applied mathematics”. MIMS Nick Higham Linear Algebra in the UK 20 / 53 History of Gaussian Elimination Chinese used variant of GE in Nine Chapters of the Mathematical Art. Gauss developed GE for his work in linear regression theory. GE first appears in Theoria Motus (1809). Variants of GE went by various names in the first half of 20th century: the bordering method, the escalator method (for matrix inversion), the square root method (Cholesky factorization), pivotal condensation, Doolittle’s method and Crout’s method. MIMS Nick Higham Linear Algebra in the UK 21 / 53 MIMS Nick Higham Linear Algebra in the UK 22 / 53 MIMS Nick Higham Linear Algebra in the UK 22 / 53 MIMS Nick Higham Linear Algebra in the UK 22 / 53 MIMS Nick Higham Linear Algebra in the UK 22 / 53 MIMS Nick Higham Linear Algebra in the UK 22 / 53 MIMS Nick Higham Linear Algebra in the UK 22 / 53 MIMS Nick Higham Linear Algebra in the UK 23 / 53 MIMS Nick Higham Linear Algebra in the UK 23 / 53 MIMS Nick Higham Linear Algebra in the UK 23 / 53 MIMS Nick Higham Linear Algebra in the UK 23 / 53 MIMS Nick Higham Linear Algebra in the UK 23 / 53 Outline MIMS 1 Matrices 2 Applications 3 History 4 Machines and Computation 5 Towards Exascale Nick Higham Linear Algebra in the UK 24 / 53 William Thomson (Lord Kelvin, 1824–1907) On a Machine for the Solution of Simultaneous Equations, Proc Roy Soc, 1878. Proposed a system involving tilting plates, cords, pulleys, for 8–10 unknowns. Suggested iterative refinement: “There is, of course, no limit to the accuracy thus obtainable by successive approximations.” Actual system for 9 unknowns built by Wilbur (1936) at MIT. Tapes 60ft long. For 3 sig figs, about 3 times faster than human with desk calculator. MIMS Nick Higham Linear Algebra in the UK 25 / 53 R. R. M. Mallock’s Machine (1933) Experimental analogue m/c (variable coil transformers) for solving 6 lin eqns built & tested in 1931. M/c for 10 equations built by Cambridge Instrument Co. Accurate to ≈ 1% of largest component. Cost ≈ £2000. Aware of conditioning issue: “if the equations are ill-conditioned, these errors may be serious”. Used equilibration and iterative refinement. “The machine could not adequately deal with ill conditioned equations, letting out a very sharp whistle when equilibrium could not be reached” (Croarken). MIMS Nick Higham Linear Algebra in the UK 26 / 53 Lord Vivian Bowden (1910–1989) Many years ago we made out of half a dozen transformers a simple and rather inaccurate machine for solving simultaneous equations—the solutions being represented as flux in the cores of the transformers. During the course of our experiments we set the machine to solve the equations— X +Y +Z =1 X +Y +Z =2 X +Y +Z =3 The machine reacted sharply— it blew the main fuse and put all the lights out. — B. V. BOWDEN, The Organization of a Typical Machine (1953) MIMS Nick Higham Linear Algebra in the UK 27 / 53 Lewis Fry Richardson (1881–1953) Num soln of PDEs (1910): finitedifference methods, Richardson extrapolation (“deferred approach to the limit”). Richardson’s method: xk +1 = xk + αk (Axk − b). Met. office, 1913–1916; Paisley College, 1929–1940. First to apply mathematics, in particular the method of finite differences, to weather prediction: Weather Prediction by Numerical Process, 1922 (2ed, 2007). MIMS Nick Higham Linear Algebra in the UK 28 / 53 Richardson on Weather Forecasting “The detailed example of Ch. IX was worked out in France in the intervals of transporting wounded in 1916–1918. During the battle of Champagne in April 1917 the working copy was sent to the rear, where it became lost, to be re-discovered some months later under a heap of coal.” MIMS Nick Higham Linear Algebra in the UK 29 / 53 Richardson on Weather Forecasting “The detailed example of Ch. IX was worked out in France in the intervals of transporting wounded in 1916–1918. During the battle of Champagne in April 1917 the working copy was sent to the rear, where it became lost, to be re-discovered some months later under a heap of coal.” “Perhaps some day in the dim future it will be possible to advance the computations faster than the weather advances . . . But that is a dream.” MIMS Nick Higham Linear Algebra in the UK 29 / 53 Richardson on Weather Forecasting “The detailed example of Ch. IX was worked out in France in the intervals of transporting wounded in 1916–1918. During the battle of Champagne in April 1917 the working copy was sent to the rear, where it became lost, to be re-discovered some months later under a heap of coal.” “Perhaps some day in the dim future it will be possible to advance the computations faster than the weather advances . . . But that is a dream.” “Imagine a large hall like a theatre. . . the walls of this chamber are painted to form a map of the globe.. . . A myriad computers are at work upon the weather of the part of the map where each sits, but each computer attends only to one equation or part of an equation.” MIMS Nick Higham Linear Algebra in the UK 29 / 53 Forecast Factory Artist’s impression: Francois Schuiten. MIMS Nick Higham Linear Algebra in the UK 30 / 53 Richard Vynne Southwell (1888–1970) Relaxation method for Ax = b. Examine patterns & relative magnitudes of residuals, identify best way to reduce them. “Like a game of chess” (Fox). Cgce acceleration: terms overrelaxation, underrelaxation coined. Multigrid ideas used. Relaxation Methods in Engineering Science, 1940. Relaxation Methods in Theoretical Physics, 1946. “Any attempt to mechanize relaxation methods would be a waste of time” (quoted by Young, 1990). MIMS Nick Higham Linear Algebra in the UK 31 / 53 MIMS Nick Higham Linear Algebra in the UK 32 / 53 2D Flow Round Aerofoil MIMS Nick Higham Linear Algebra in the UK 33 / 53 Leslie Fox (1918–1992) PhD (1942) with Southwell. “Outstanding exponent of relaxation method”. Mathematics Division, NPL, 1945–1956. Set up Oxford Univ Computing Lab., 1957. 1950s papers on A−1 , Ax = b. An Introduction to Numerical Linear Algebra, 1964. Early textbook treatment of computational aspects. First textbook to describe Wilkinson’s backward error analysis. MIMS Nick Higham Linear Algebra in the UK 34 / 53 James Hardy Wilkinson (1919–1986) MIMS Nick Higham Linear Algebra in the UK 35 / 53 Enter Cambridge University Second World War National Physical Laboratory Elected Fellow of the Royal Society Turing Wilkinson Kings College, 1931 Bletchley Park; breaks the Enigma code. 1945: Senior Scientific Officer Trinity College, 1936 Proposal for Development . . . of ACE 1948–51: Head of Pilot ACE group. 1951–56: Works on exploitation of Pilot ACE for solving scientific problems 1969 1951 Ordnance Board of Ministry of Supply 1946: Working half time each with Turing and Desk Computing Group Gaussian Elimination at NPL 1946 Fox, Goodwin, Turing & Wilkinson solve 18 × 18 system on desk calculator in 2 weeks. Obtained small residual. 1948 Fox, Huskey & Wilkinson give empirical evidence in support of GE, even for ill conditioned matrices. 1948 Wilkinson’s confidential NPL report on the Automatic Computing Engine (ACE) gives program implementing GE with partial pivoting and iterative refinement. 1963 Wilkinson’s backward error analysis: Rounding Errors in Algebraic Processes. MIMS Nick Higham Linear Algebra in the UK 37 / 53 MIMS Nick Higham Linear Algebra in the UK 38 / 53 Turing’s Paper Rounding-Off Errors in Matrix Processes, Quart. J. Mech. and Applied Math., 1948. Proves ∃ce of A = LU; shows GE computes it. Introduces term “condition number”. Uses term “preconditioning”. Describes iterative refinement for linear systems. Exploits backward error ideas. MIMS Nick Higham Linear Algebra in the UK 39 / 53 Pilot Ace 1950 The Pilot ACE at the National Physical Laboratory runs for the first time. MIMS Nick Higham Linear Algebra in the UK 40 / 53 Linear Equation Solvers on the Pilot ACE An interesting feature of the codes is that they made a very intensive use of subroutines; the addition of two vectors, multiplication of a vector by a scalar, inner products, etc., were all coded in this way — J. H. Wilkinson MIMS Nick Higham Linear Algebra in the UK 41 / 53 Daily Mirror, 1952 MIMS Nick Higham Linear Algebra in the UK 42 / 53 MIMS Nick Higham Linear Algebra in the UK 43 / 53 Mathematicians on Flutter Olga Taussky, in Frazer’s group at NPL, 1940s. 6 × 6 QEPs from flutter in supersonic aircraft. Used Gershgorin. Peter Lancaster, English Electric Co., 1950s. QEPs, 2 ≤ n ≤ 20. MIMS Nick Higham Linear Algebra in the UK 44 / 53 Outline MIMS 1 Matrices 2 Applications 3 History 4 Machines and Computation 5 Towards Exascale Nick Higham Linear Algebra in the UK 45 / 53 TOP500, http://www.top500.org Ranks world’s fastest computers by their performance on the LINPACK benchmark. Performance measured in flops (floating point operations) per second. Updated twice a year: SC (Nov, USA) and Germany (June). User can tune provided code (C and MPI). Must obtain correct result (small residual). Must not use Strassen’s method. Tera: 1012 , Peta: 1015 , Exa: 1018 . MIMS Nick Higham Linear Algebra in the UK 46 / 53 Rank Site Computer Country Cores Rmax [Pflops] % of Peak 1 RIKEN Advanced Inst for Comp Sci K Computer Fujitsu SPARC64 VIIIfx + custom Japan 548,352 8.16 93 9.9 82 2 Nat. SuperComputer Center in Tianjin Tianhe-1A, NUDT Intel + Nvidia GPU + custom China 186,368 2.57 55 4.04 63 3 DOE / OS Oak Ridge Nat Lab Jaguar, Cray AMD + custom USA 224,162 1.76 75 7.0 25 4 Nat. Supercomputer Center in Shenzhen Nebulea, Dawning Intel + Nvidia GPU + IB China 120,640 1.27 43 2.58 49 5 GSIC Center, Tokyo Institute of Technology Tusbame 2.0, HP Intel + Nvidia GPU + IB Japan 73,278 1.19 52 1.40 85 6 DOE / NNSA LANL & SNL Cielo, Cray AMD + custom USA 142,272 1.11 81 3.98 27 NASA Ames Research Center/NAS DOE / OS Lawrence Berkeley Nat Lab Commissariat a l'Energie Atomique (CEA) Plelades SGI Altix ICE 8200EX/8400EX + IB USA 111,104 1.09 83 4.10 26 Hopper, Cray AMD + custom USA 153,408 1.054 82 2.91 36 Tera-10, Bull Intel + IB France 138,368 1.050 84 4.59 22 DOE / NNSA Los Alamos Nat Lab Roadrunner, IBM AMD + Cell GPU + IB USA 122,400 1.04 76 2.35 44 7 8 9 10 MIMS Nick Higham Linear Algebra in the UK Power GFlo [MW] Wa 47 / 53 28 Supercomputers in the UK Rank 24 65 69 70 93 154 160 186 190 191 211 212 213 228 233 234 278 279 339 351 365 404 405 415 416 482 484 MIMS Site Computer University of Edinburgh Cray XE6 12-core 2.1 GHz Atomic Weapons Establishment Bullx B500 Cluster, Xeon X56xx 2.8Ghz, QDR Infiniband ECMWF Power 575, p6 4.7 GHz, Infiniband ECMWF Power 575, p6 4.7 GHz, Infiniband University of Edinburgh Cray XT4, 2.3 GHz University of Southampton iDataPlex, Xeon QC 2.26 GHz, Ifband, Windows HPC2008 R2 IT Service Provider Cluster Platform 4000 BL685c G7, Opteron 12C 2.2 Ghz, GigE IT Service Provider Cluster Platform 3000 BL460c G7, Xeon X5670 2.93 Ghz, GigE Computacenter (UK) LTD Cluster Platform 3000 BL460c G1, Xeon L5420 2.5 GHz, GigE Classified xSeries x3650 Cluster Xeon QC GT 2.66 GHz, Infiniband Classified BladeCenter HS22 Cluster, WM Xeon 6-core 2.66Ghz, Ifband Classified BladeCenter HS22 Cluster, WM Xeon 6-core 2.66Ghz, Ifband Classified BladeCenter HS22 Cluster, WM Xeon 6-core 2.66Ghz, Ifband IT Service Provider Cluster Platform 4000 BL685c G7, Opteron 12C 2.1 Ghz, GigE Financial Institution iDataPlex, Xeon X56xx 6C 2.66 GHz, GigE Financial Institution iDataPlex, Xeon X56xx 6C 2.66 GHz, GigE UK Meteorological Office Power 575, p6 4.7 GHz, Infiniband UK Meteorological Office Power 575, p6 4.7 GHz, Infiniband Cluster Platform 3000 BL460c, Xeon 54xx 3.0GHz, Computacenter (UK) LTD GigEthernet Asda Stores BladeCenter HS22 Cluster, WM Xeon 6-core 2.93Ghz, GigE Financial Services xSeries x3650M2 Cluster, Xeon QC E55xx 2.53 Ghz, GigE Financial Institution BladeCenter HS22 Cluster, Xeon QC GT 2.53 GHz, GigEthernet Financial Institution BladeCenter HS22 Cluster, Xeon QC GT 2.53 GHz, GigEthernet Bank xSeries x3650M3, Xeon X56xx 2.93 GHz, GigE Bank xSeries x3650M3, Xeon X56xx 2.93 GHz, GigE IT Service Provider Cluster Platform 3000 BL460c G6, Xeon L5520 2.26 GHz, GigE IT Service Provider Cluster Platform 3000 BL460c G6, Xeon X5670 2.93 GHz, 10G Nick Higham Linear Algebra in the UK Cores 44376 12936 8320 8320 12288 8000 14556 9768 11280 6368 5880 5880 5880 12552 9480 9480 3520 3520 Rmax Tflop/s 279 124 115 115 95 66 65 59 58 58 55 55 55 54 53 53 51 51 7560 8352 8096 7872 7872 7728 7728 8568 4392 47 47 46 44 44 43 43 40 40 48 / 53 59 PFlop/s 100 Pflop/s 100000000 10 Pflop/s 8.2 PFlop/s 10000000 1 Pflop/s 1000000 100 Tflop/s SUM 100000 41 TFlop/s 10 Tflop/s 10000 1 Tflop/s 1000 N=1 1.17 TFlop/s 6-8 years 100 Gflop/s 100 N=500 59.7 GFlop/s 10 Gflop/s 10 My Laptop (6 Gflop/s) 1 Gflop/s 1 100 Mflop/s 0.1 MIMS My iPad2 (620 Mflop/s) 400 MFlop/s 1993 1995 1997 Nick Higham 1999 2001 2003 2005 2007 Linear Algebra in the UK 2009 2011 49 / 53 MIMS Nick Higham Linear Algebra in the UK 50 / 53 Need for Software Redesign Fast ascent terascale → petascale → exascale. Extreme parallelism & hybrid design. Limits on power/clock speed. Reducing communication essential. Fault tolerance required. MIMS Nick Higham Linear Algebra in the UK 51 / 53 Issues for Exascale Synchronization-reducing algorithms. Communication-reducing algorithms. Fault resilient algorithms. Mixed precision methods. Reproducibility of results. Rethink our approach to Ax = b. MIMS Nick Higham Linear Algebra in the UK 52 / 53 Asynchronous Jacobi EPSRC project Novel Asynchronous Algorithms and Software for Large Sparse Systems, 2010–2014 (Manchester, Edinburgh, Hull, Leeds & Strathclyde). Avge iterations 250 200 150 100 50 0 2 4 6 8 10 12 14 16 18 20 22 24 16 18 20 22 24 Time (secs) 8000 7000 6000 5000 4000 MIMS 0 2 4 Nick Higham 6 8 10 12 14 Linear Algebra in the UK 53 / 53 References I D. J. Albers and G. L. Alexanderson, editors. Mathematical People: Profiles and Interviews. Birkhäuser, Boston, MA, USA, 1985. B. V. Bowden. The organization of a typical machine. In B. V. Bowden, editor, Faster than Thought: A Symposium on Digital Computing Machines, pages 67–77. Pitman, London, 1953. M. Brown and D. G. Lowe. Automatic panoramic image stitching using invariant features. Int. J. Computer Vision, 74(1):59–73, 2007. MIMS Nick Higham Linear Algebra in the UK 44 / 53 References II T. Crilly. Arthur Cayley: Mathematician Laureate of the Victorian Age. Johns Hopkins University Press, Baltimore, MD, USA, 2006. M. R. Cullen. Linear Models in Biology. Ellis Horwood, Chichester, 1985. J. J. Dongarra, P. Luszczek, and A. Petitet. The LINPACK benchmark: Past, present and future. Concurrency and Computation: Practice and Experience, 15:803–820, 2003. MIMS Nick Higham Linear Algebra in the UK 45 / 53 References III L. Fox. Early numerical analysis in the United Kingdom. In S. G. Nash, editor, A History of Scientific Computing, pages 280–300. Addison-Wesley, Reading, MA, USA, 1990. R. A. Frazer, W. J. Duncan, and A. R. Collar. Elementary Matrices and Some Applications to Dynamics and Differential Equations. Cambridge University Press, Cambridge, UK, 1938. 1963 printing. J. F. Grcar. How ordinary elimination became Gaussian elimination. Historia Mathematica, 38(2):163–218, 2011. MIMS Nick Higham Linear Algebra in the UK 46 / 53 References IV J. F. Grcar. Mathematics of Gaussian elimination. Notices Amer. Math. Soc., 58(8):782–792, 2011. D. A. Grier. When Computers Were Human. Princeton University Press, Princeton, NJ, USA, 2005. D. J. Higham and A. Taylor. The sleekest link algorithm. Mathematics Today, 39(6):192–197, 2003. MIMS Nick Higham Linear Algebra in the UK 47 / 53 References V N. J. Higham. An interview with Peter Lancaster. Numerical Analysis Report No. 468, Manchester Centre for Computational Mathematics, Manchester, England, June 2005. D. C. Joyce. Survey of extrapolation processes in numerical analysis. SIAM Rev., 13(4):435–490, 1971. JPEG file interchange format, version 1.02. http: //www.w3.org/Graphics/JPEG/jfif3.pdf. MIMS Nick Higham Linear Algebra in the UK 48 / 53 References VI P. Lancaster. Lambda-Matrices and Vibrating Systems. Pergamon Press, Oxford, 1966. Reprinted by Dover, New York, 2002. A. N. Langville and C. D. Meyer. Google’s PageRank and Beyond: The Science of Search Engine Rankings. Princeton University Press, Princeton, NJ, USA, 2006. R. R. M. Mallock. An electrical calculating machine. Proc. Royal Society, Series A, 140(841):457–483, 1933. MIMS Nick Higham Linear Algebra in the UK 49 / 53 References VII National Physical Laboratory. Modern Computing Methods. Number 16 in Notes on Applied Science. Her Majesty’s Stationery Office, London, 1957. K. H. Parshall. James Joseph Sylvester. Jewish Mathematician in a Victorian World. Johns Hopkins University Press, Baltimore, MD, USA, 2006. L. F. Richardson. Weather Prediction by Numerical Process. Cambridge University Press, Cambridge, UK, 1922. MIMS Nick Higham Linear Algebra in the UK 50 / 53 References VIII R. V. Southwell. Relaxation Methods in Engineering Science: A Treatise on Approximate Computation. Oxford University Press, 1940. R. V. Southwell. Relaxation Methods in Theoretical Physics: A Continuation of the Treatise ‘Relaxation Methods in Engineering Science’. Oxford University Press, 1946. O. Taussky. How I became a torchbearer for matrix theory. Amer. Math. Monthly, 95(9):801–812, Nov. 1988. MIMS Nick Higham Linear Algebra in the UK 51 / 53 References IX O. Taussky and J. Todd. Cholesky, Toeplitz and the triangular factorization of symmetric matrices. Numer. Algorithms, 41:197–202, 2006. W. Thomson. On a machine for the solution of simultaneous equations. Proc. Royal Society, 28:111–113, 1878-1879. J. B. Wilbur. The mechanical solution of simultaneous equations. J. Franklin Inst., 222(6):715–724, 1936. MIMS Nick Higham Linear Algebra in the UK 52 / 53 References X D. M. Young. A historical review of iterative methods. In S. G. Nash, editor, A History of Scientific Computing, pages 180–194. Addison-Wesley, Reading, MA, USA, 1990. MIMS Nick Higham Linear Algebra in the UK 53 / 53