English

Monotonicity of the Lebesgue constant for equally spaced knots

Numerical Analysis 2011-03-11 v1

Abstract

Let ti=int_{i}=\frac{i}{n} for i=0,...,ni=0,...,n be equally spaces knots in the unit interval [0,1].[0,1]. Let Sn\mathcal{S}_{n} be the space of piecewise linear continuous functions on [0,1][0,1] with knots πn={ti:0in}.\pi_{n}=\{t_{i}:0\leq i\leq n\}. Then we have the orthogonal projection PnP_{n} of L2([0,1])L^{2}([0,1]) onto Sn.\mathcal{S}_{n}. In Section 1 we collect a few preliminary facts about the solutions of the recurrence fk14fk+fk+1=0f_{k-1}-4f_{k}+f_{k+1}=0 that we need in Section 2 to show that the sequence % a_{n}=\Vert P_{n}\Vert_{1} of L1L^{1}-norms of these projection operators is strictly increasing.

Keywords

Cite

@article{arxiv.1103.1949,
  title  = {Monotonicity of the Lebesgue constant for equally spaced knots},
  author = {Markus Passenbrunner},
  journal= {arXiv preprint arXiv:1103.1949},
  year   = {2011}
}