Abstract
In this article, we study the problem of best L 1 approximation of Heaviside-type functions from Chebyshev and weak-Chebyshev spaces. We extend the Hobby-Rice theorem (Proc. Am. Math. Soc., 16, 665–670, 1965) into an appropriate framework and prove the unicity of best L 1 approximation of Heaviside-type functions from an even-dimensional Chebyshev space under some assumptions on the dimension of the subspaces composed of the odd and even functions. We also apply the results to compute best L 1 approximations of Heaviside-type functions by polynomials and Hermite polynomial splines with fixed knots.
Similar content being viewed by others
References
Bustamante, J., Quesada, J., Martínez-Cruz, R.: Best one-sided L 1 approximation to the Heaviside and sign functions. Journal of Approximation Theory 164, 791–802 (2012)
Gajny, L., Gibaru, O., Nyiri, E.: L 1 C 1 polynomial spline approximation algorithms for large data sets. Numer. Algorithms 67, 807–826 (2014)
Hobby, C., Rice, J.: A moment problem in L 1 approximation. Proc. Am. Math. Soc. 16, 665–670 (1965)
James, R.C.: Orthogonality and linear functionals in normed linear spaces. Trans. Am. Math. Soc. 61, 265–292 (1947)
Kammler, D.: L 1-Approximation of completely monotonic functions by sums of exponentials. SIAM J. Numer. Anal. 16, 30–45 (1979)
Karlin, S., Studden, W.: Tchebycheff systems: with applications in analysis and statistics (1966)
Krein, M., Noudelman, A., Louvish, D.: The Markov moment problem and extremal problems: [ideas and problems of P. L. Čebyšev and A. A. Markov and their further development], Translations of mathematical monographs, American Mathematical Society, Providence (R.I.), 1977. Trad. de: Problema momentov Markova i kstremalnye zadachi
Kripke, B., Rivlin, T.: Approximation in the metric of L 1(X, μ). Trans. Am. Math. Soc. 119, 101–122 (1965)
Micchelli, C.: Best L 1 approximation by weak Chebyshev systems and the uniqueness of interpolating perfect splines. Journal of Approximation Theory 19, 1–14 (1977)
Moskona, E., Petrushev, P., Saff, E.B.: The Gibbs phenomenon for best L 1-trigonometric polynomial approximation. Constr. Approx. 11, 391–416 (1995)
Nirenberg, L.: Topics in nonlinear functional analysis: notes by R. A Artino. Courant Inst. of Math. Sciences (1974)
Nürnberger, G.: Approximation by Spline Functions. Springer (2013)
Peherstorfer, F.: Trigonometric polynomial approximation in the L 1-norm. Math. Z. 169, 261–269 (1979)
Phelps, R.R.: Čebyšev subspaces of finite dimension in L 1. Proc. Am. Math. Soc. 17, 646–652 (1966)
Pinkus, A.: A simple proof of the Hobby-Rice theorem. Proc. Am. Math. Soc. 60, 82–84 (1976)
Pinkus, A.: On L 1-approximation, Cambridge tracts in mathematics, Cambridge University Press, Cambridge, England, New York (1989)
Rice, J.: On the computation of L 1 approximations by exponentials, rationals, and other functions. Math. Comput. 18, 390–396 (1964)
Rice, J.: The approximation of functions. Volume 1, linear theory (1964)
Saff, E.B., Tashev, S.: Gibbs phenomenon for best L p approximation by polygonal lines. East Journal on Approximations 5, 235–251 (1999)
Schumaker, L.: Spline functions: basic theory, Pure and applied mathematics, J. Wiley, New York, Chichester, Brisbane (1981)
Strauss, H.: Best L 1-approximation. Journal of Approximation Theory 41, 297–308 (1984)
Usow, K.: On L 1 approximation I: computation for continuous functions and continuous dependence. SIAM J. Numer. Anal. 4, 70–88 (1967)
Wang, Z., Fang, S.-C., Lavery, J.: On shape-preserving capability of cubic L 1 spline fits. Comput. Aided Geom. Des. 40, 59–75 (2015)
Zielke, R.: Discontinuous Chebyshev systems. Springer, Berlin and New York (1979)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Gajny, L., Gibaru, O., Nyiri, E. et al. Best L 1 approximation of Heaviside-type functions from Chebyshev and weak-Chebyshev spaces. Numer Algor 75, 827–843 (2017). https://doi.org/10.1007/s11075-016-0222-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11075-016-0222-8