1. On the Approximation of Singular Functions by Series of Non-integer Powers
- Author
-
Zhao, Mohan and Serkh, Kirill
- Subjects
Mathematics - Numerical Analysis ,41A30, 41A58, 65D15 - Abstract
In this paper, we describe an algorithm for approximating functions of the form $f(x) = < \sigma(\mu), x^\mu >$ over $[0,1] \subset \mathbb{R}$, where $\sigma(\mu)$ is some distribution supported on $[a,b]$, with $0 $, where $a\leq c \leq b$ and $m \geq 0$ is an integer. Given the desired accuracy $\epsilon$ and the values of $a$ and $b$, our method determines a priori a collection of non-integer powers $t_1$, $t_2$, $\ldots$, $t_N$, so that the functions are approximated by series of the form $f(x)\approx \sum_{j=1}^N c_j x^{t_j}$, and a set of collocation points $x_1$, $x_2$, $\ldots$, $x_N$, such that the expansion coefficients can be found by collocating the function at these points. We prove that our method has a small uniform approximation error which is proportional to $\epsilon$ multiplied by some small constants. We demonstrate the performance of our algorithm with several numerical experiments, and show that the number of singular powers and collocation points grows as $N=O(\log{\frac{1}{\epsilon}})$.
- Published
- 2023