2002/08/26 by S. Gluzman, V. I. Yukalov, D. Sornette +1 · 1 citation
Mathematics · Physics and Astronomy · #Applied mathematics #Class (philosophy) #Complement (music) #Computer science #Convergence (economics) #Exponential function #Fractional Differential Equations Solutions #Iterative Methods for Nonlinear Equations #Limit (mathematics) #Mathematical analysis #Mathematical functions and polynomials #Mathematics #Padé approximant #Type (biology) #cond-mat.stat-mech
paper · pdf · doi:10.1103/physreve.67.026109
published as Physical Review E 67 (2), art. 026109, DOI: 10.1103 (2003) · 22 pages + 11 ps figures
arxiv created 2002/08/26 · openalex publication_date 2003/02/12 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The problem of reconstructing functions from their asymptotic expansions in powers of a small variable is addressed by deriving an improved type of approximants. The derivation is based on the self-similar approximation theory, which presents the passage from one approximant to another as the motion realized by a dynamical system with the property of group self-similarity. The derived approximants, because of their form, are called self-similar factor approximants. These complement the obtained earlier self-similar exponential approximants and self-similar root approximants. The specific feature of self-similar factor approximants is that their control functions, providing convergence of the computational algorithm, are completely defined from the accuracy-through-order conditions. These approximants contain the Padé approximants as a particular case, and in some limit they can be reduced to the self-similar exponential approximants previously introduced by two of us. It is proved that the self-similar factor approximants are able to reproduce exactly a wide class of functions, which include a variety of nonalgebraic functions. For other functions, not pertaining to this exactly reproducible class, the factor approximants provide very accurate approximations, whose accuracy surpasses significantly that of the most accurate Padé approximants. This is illustrated by a number of examples showing the generality and accuracy of the factor approximants even when conventional techniques meet serious difficulties.