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In this note we formulate some questions in the study of approximations of reals by rationals of the form a/b^2 arising in theory of Shr"odinger equations. We hope to attract attention of specialists to this natural subject of number…

Number Theory · Mathematics 2007-05-23 Oleg Karpenkov

We study how well a real number can be approximated by sums of two or more rational numbers with denominators up to a certain size.

Number Theory · Mathematics 2007-05-23 Tsz Ho Chan , Angel V. Kumchev

We explore an algorithm for approximating roots of integers, discuss its motivation and derivation, and analyze its convergence rates with varying parameters and inputs. We also perform comparisons with established methods for approximating…

Numerical Analysis · Mathematics 2021-01-11 William Gerst

We describe an approximate rational arithmetic with round-off errors (both absolute and relative) controlled by the user. The rounding procedure is based on the continued fraction expansion of real numbers. Results of computer experiments…

Numerical Analysis · Mathematics 2025-10-20 Grigori Litvinov , Anatoli Rodionov , Andrei Chourkin

We consider the question of approximating any real number $\alpha$ by sums of $n$ rational numbers $\frac{a_1}{q_1} + \frac{a_2}{q_2} + ... + \frac{a_n}{q_n}$ with denominators $1 \leq q_1, q_2, ..., q_n \leq N$. This leads to an inquiry on…

Number Theory · Mathematics 2007-05-23 Tsz Ho Chan

We present a complete algorithm for finding an exact minimal polynomial from its approximate value by using an improved parameterized integer relation construction method. Our result is superior to the existence of error controlling on…

Symbolic Computation · Computer Science 2010-01-06 Xiaolin Qin , Yong Feng , Jingwei Chen , Jingzhong Zhang

Potential theory for rational approximation is reviewed by means of examples computed with the AAA algorithm.

Numerical Analysis · Mathematics 2025-01-03 Lloyd N. Trefethen

We seek random versions of some classical theorems on complex approximation by polynomials and rational functions, as well as investigate properties of random compact sets in connection to complex approximation.

Complex Variables · Mathematics 2017-09-26 Simon St-Amant , Jérémie Turcotte

A rational approximation by a ratio of polynomial functions is a flexible alternative to polynomial approximation. In particular, rational functions exhibit accurate estimations to nonsmooth and non- Lipschitz functions, where polynomial…

Optimization and Control · Mathematics 2020-02-27 V. Peiris , N. Sharon , N. Sukhorukova J. Ugon

We generalize Dirichlet's diophantine approximation theorem to approximating any real number $\alpha$ by a sum of two rational numbers $\frac{a_1}{q_1} + \frac{a_2}{q_2}$ with denominators $1 \leq q_1, q_2 \leq N$. This turns out to be…

Number Theory · Mathematics 2007-05-23 Tsz Ho Chan

We present a new algorithm for reconstructing an exact algebraic number from its approximate value using an improved parameterized integer relation construction method. Our result is consistent with the existence of error controlling on…

Computational Complexity · Computer Science 2009-02-06 Xiaolin Qin , Yong Feng , Jingwei Chen , Jingzhong Zhang

We present a new rational approximation algorithm based on the empirical interpolation method for interpolating a family of parametrized functions to rational polynomials with invariant poles, leading to efficient numerical algorithms for…

Numerical Analysis · Mathematics 2025-01-23 Aidi Li , Yuwen Li

In this paper, we propose a new and simple approach to the approximation algorithms that are modified and improved from our published results. The computational and graphical examples are presented with the aid of Maple procedures.

Numerical Analysis · Mathematics 2025-06-24 Quan Le Phuong

In this paper we consider a family of algorithms for approximate implicitization of rational parametric curves and surfaces. The main approximation tool in all of the approaches is the singular value decomposition, and they are therefore…

Numerical Analysis · Mathematics 2016-05-30 Oliver J. D. Barrowclough , Tor Dokken

A subalgebraic approximation algorithm is proposed to estimate from a set of time series the parameters of the observer representation of a discrete-time polynomial system without inputs which can generate an approximation of the observed…

Optimization and Control · Mathematics 2015-07-09 Jana Němcová , Mihály Petreczky , Jan H. van Schuppen

For a given irrational number, we consider the properties of best rational approximations of given parities. There are three different kinds of rational numbers according to the parity of the numerator and denominator, say odd/odd, even/odd…

Number Theory · Mathematics 2024-03-20 Dong Han Kim , Seul Bee Lee , Lingmin Liao

In the present paper we are concerned with a numerical algorithm for the approximation of the two-dimensional neural field equation with delay. We consider three numerical examples that have been analysed before by other authors and are…

Numerical Analysis · Mathematics 2015-11-04 Pedro M. Lima , Evelyn Buckwar

In this paper we describe an algorithm for implicitizing rational hypersurfaces in case there exists at most a finite number of base points. It is based on a technique exposed in math.AG/0210096, where implicit equations are obtained as…

Algebraic Geometry · Mathematics 2007-05-23 Laurent Buse , Marc Chardin

The AAA algorithm for rational approximation is employed to illustrate applications of rational functions all across numerical analysis.

Numerical Analysis · Mathematics 2025-10-21 Yuji Nakatsukasa , Lloyd N. Trefethen

In this paper, we propose a method to obtain a constrained approximation of a rational B\'{e}zier curve by a polynomial B\'{e}zier curve. This problem is reformulated as an approximation problem between two polynomial B\'{e}zier curves…

Numerical Analysis · Mathematics 2014-09-16 Mao Shi , Jiansong Deng
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