On numerical stability of continued fractions

The paper considers the numerical stability of the backward recurrence algorithm (BR-algorithm) for computing approximants of the continued fraction with complex elements. The new method establishes sufficient conditions for the numerical stability of this algorithm and the error bounds of the calcu...

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Main Authors: V. Hladun, V. Кravtsiv, M. Dmytryshyn, R. Rusyn
Format: Article
Language:German
Published: Ivan Franko National University of Lviv 2024-12-01
Series:Математичні Студії
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Online Access:http://matstud.org.ua/ojs/index.php/matstud/article/view/558
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author V. Hladun
V. Кravtsiv
M. Dmytryshyn
R. Rusyn
author_facet V. Hladun
V. Кravtsiv
M. Dmytryshyn
R. Rusyn
author_sort V. Hladun
collection DOAJ
description The paper considers the numerical stability of the backward recurrence algorithm (BR-algorithm) for computing approximants of the continued fraction with complex elements. The new method establishes sufficient conditions for the numerical stability of this algorithm and the error bounds of the calculation of the $n$th approximant of the continued fraction with complex elements. It follows from the obtained conditions that the numerical stability of the algorithm depends not only on the rounding errors of the elements and errors of machine operations but also on the value sets and the element sets of the continued fraction. The obtained results were used to study the numerical stability of the BR-algorithm for computing the approximants of the continued fraction expansion of the ratio of Horn's confluent functions $\mathrm{H}_7$. Bidisc and bicardioid regions are established, which guarantee the numerical stability of the BR-algorithm. The obtained result is applied to the study of the numerical stability of computing approximants of the continued fraction expansion of the ratio of Horn's confluent function $\mathrm{H}_7$ with complex parameters. In addition, the analysis of the relative errors arising from the computation of approximants using the backward recurrence algorithm, the forward recurrence algorithm, and Lenz's algorithm is given. The method for studying the numerical stability of the BR-algorithm proposed in the paper can be used to study the numerical stability of the branched continued fraction expansions and numerical branched continued fractions with elements in angular and parabolic domains.
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spelling doaj-art-8f0876f66f514cd18c0a01c04ab35bb12025-07-08T09:02:48ZdeuIvan Franko National University of LvivМатематичні Студії1027-46342411-06202024-12-0162216818310.30970/ms.62.2.168-183558On numerical stability of continued fractionsV. Hladun0V. Кravtsiv1M. Dmytryshyn2R. Rusyn3Lviv Polytechnic National University, Lviv, UkraineVasyl Stefanyk Precarpathian National University, Ivano-Frankivsk, UkraineWest Ukrainian National University, Ternopil, UkraineVasyl Stefanyk Precarpathian National University, Ivano-Frankivsk, UkraineThe paper considers the numerical stability of the backward recurrence algorithm (BR-algorithm) for computing approximants of the continued fraction with complex elements. The new method establishes sufficient conditions for the numerical stability of this algorithm and the error bounds of the calculation of the $n$th approximant of the continued fraction with complex elements. It follows from the obtained conditions that the numerical stability of the algorithm depends not only on the rounding errors of the elements and errors of machine operations but also on the value sets and the element sets of the continued fraction. The obtained results were used to study the numerical stability of the BR-algorithm for computing the approximants of the continued fraction expansion of the ratio of Horn's confluent functions $\mathrm{H}_7$. Bidisc and bicardioid regions are established, which guarantee the numerical stability of the BR-algorithm. The obtained result is applied to the study of the numerical stability of computing approximants of the continued fraction expansion of the ratio of Horn's confluent function $\mathrm{H}_7$ with complex parameters. In addition, the analysis of the relative errors arising from the computation of approximants using the backward recurrence algorithm, the forward recurrence algorithm, and Lenz's algorithm is given. The method for studying the numerical stability of the BR-algorithm proposed in the paper can be used to study the numerical stability of the branched continued fraction expansions and numerical branched continued fractions with elements in angular and parabolic domains.http://matstud.org.ua/ojs/index.php/matstud/article/view/558continued fractionnumerical approximationroundoff error
spellingShingle V. Hladun
V. Кravtsiv
M. Dmytryshyn
R. Rusyn
On numerical stability of continued fractions
Математичні Студії
continued fraction
numerical approximation
roundoff error
title On numerical stability of continued fractions
title_full On numerical stability of continued fractions
title_fullStr On numerical stability of continued fractions
title_full_unstemmed On numerical stability of continued fractions
title_short On numerical stability of continued fractions
title_sort on numerical stability of continued fractions
topic continued fraction
numerical approximation
roundoff error
url http://matstud.org.ua/ojs/index.php/matstud/article/view/558
work_keys_str_mv AT vhladun onnumericalstabilityofcontinuedfractions
AT vkravtsiv onnumericalstabilityofcontinuedfractions
AT mdmytryshyn onnumericalstabilityofcontinuedfractions
AT rrusyn onnumericalstabilityofcontinuedfractions