Abstract

We look at two classical examples in the theory of numerical analysis, namely, the Runge example for interpolation and Wilkinson's example (actually two examples) for rootfinding. We use the modern theory of backward error analysis and conditioning, as instigated and popularized by Wilkinson but refined by Farouki and Rajan. By this means, we arrive at a satisfactory explanation of the puzzling phenomena encountered by students when they try to fit polynomials to numerical data, or when they try to use numerical rootfinding to find polynomial zeros. Computer algebra, with its controlled, arbitrary precision, plays an important didactic role.

Keywords

  1. interpolation
  2. rootfinding
  3. conditioning
  4. sensitivity

MSC codes

  1. 97N40

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References

1.
F. Acton, Numerical Methods that Work, MAA Spectrum, Mathematical Association of America, 1990.
2.
A. Amiraslani, New Algorithms for Matrices, Polynomials and Matrix Polynomials, Ph.D. thesis, Western University, Ontario, Canada, 2006.
3.
B. Beckermann, The condition number of real Vandermonde, Krylov and positive definite Hankel matrices, Numer. Math., 85 (2000), pp. 553--577.
4.
R. Burden, D. Faires, and A. Burden, Numerical Analysis, 10th ed., Cengage Learning, Boston, MA, 2016.
5.
J. Carnicer, Y. Khiar, and J. Pen͂a, Optimal stability of the Lagrange formula and conditioning of the Newton formula, J. Approx. Theory, 238 (2019), pp. 52--66.
6.
R. M. Corless and N. Fillion, A Graduate Introduction to Numerical Methods: From the Viewpoint of Backward Error Analysis, Springer, 2013, https://doi.org/10.1007/978-1-4614-8453-0.
7.
R. M. Corless and S. M. Watt, Bernstein bases are optimal, but, sometimes, Lagrange bases are better, in Proceedings of SYNASC, Timisoara, MIRTON Press, 2004, pp. 141--153.
8.
T. A. Driscoll and R. J. Braun, Fundamentals of Numerical Computation, SIAM, 2018.
9.
R. Farouki and T. Goodman, On the optimal stability of the Bernstein basis, Math. Comp., 65 (1996), pp. 1553--1566.
10.
R. Farouki and V. Rajan, On the numerical condition of polynomials in Bernstein form, Comput. Aided Geom. Design, 4 (1987), pp. 191--216.
11.
W. Gautschi, Numerical Analysis, Birkhäuser Boston, 2011.
12.
T. Gowers, J. Barrow-Green, and I. Leader, The Princeton Companion to Mathematics, Princeton University Press, 2010.
13.
K. Green and T. Wagenknecht, Pseudospectra and delay differential equations, J. Comput. Appl. Math., 196 (2006), pp. 567--578.
14.
R. Hamming, Numerical Methods for Scientists and Engineers, Dover, 2012.
15.
P. Henrici, Elements of Numerical Analysis, Tech. report, 1964.
16.
P. Henrici, Essentials of Numerical Analysis with Pocket Calculator Demonstrations, John Wiley & Sons, 1982.
17.
N. J. Higham, Accuracy and Stability of Numerical Algorithms, 2nd ed., SIAM, 2002, https://doi.org/10.1137/1.9780898718027.
18.
N. J. Higham and T. Mary, A new approach to probabilistic rounding error analysis, SIAM J. Sci. Comput., 41 (2019), pp. A2815--A2835, https://doi.org/10.1137/18M1226312.
19.
D. Kahaner, C. Moler, and S. Nash, Numerical Methods and Software, Prentice-Hall, 1989.
20.
T. Sauer, Numerical Analysis, Pearson, 2011.
21.
L. N. Trefethen, Approximation Theory and Approximation Practice, SIAM, 2013.
22.
J. H. Wilkinson, The perfidious polynomial, in Studies in Numerical Analysis, MAA Stud. Math. 24, MAA, 1984, pp. 1--28.

Information & Authors

Information

Published In

cover image SIAM Review
SIAM Review
Pages: 231 - 243
ISSN (online): 1095-7200

History

Submitted: 17 January 2018
Accepted: 7 February 2019
Published online: 11 February 2020

Keywords

  1. interpolation
  2. rootfinding
  3. conditioning
  4. sensitivity

MSC codes

  1. 97N40

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