Stable Calculation of Discrete Hahn Functions

Generating discrete orthogonal polynomials from the recurrence or difference equation is error-prone, as it is sensitive to error propagation and dependent on highly accurate initial values. Strategies to handle this, involving control over the deviation of norm and orthogonality, have already been...

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Main Author: Albertus C. den Brinker
Format: Article
Language:English
Published: MDPI AG 2022-02-01
Series:Symmetry
Subjects:
Online Access:https://www.mdpi.com/2073-8994/14/3/437
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author Albertus C. den Brinker
author_facet Albertus C. den Brinker
author_sort Albertus C. den Brinker
collection DOAJ
description Generating discrete orthogonal polynomials from the recurrence or difference equation is error-prone, as it is sensitive to error propagation and dependent on highly accurate initial values. Strategies to handle this, involving control over the deviation of norm and orthogonality, have already been developed for the discrete Chebyshev and Krawtchouk functions, i.e., the orthonormal basis in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mn>2</mn></msub></semantics></math></inline-formula> derived from the polynomials. Since these functions are limiting cases of the discrete Hahn functions, it suggests that the strategy could also be successful there. We outline the algorithmic strategies including the specific method of generating the initial values, and show that the orthonormal basis can indeed be generated for large supports and polynomial degrees with controlled numerical error. Special attention is devoted to symmetries, as the symmetric windows are most commonly used in signal processing, allowing for simplification of the algorithm due to this prior knowledge, and leading to savings in the required computational power.
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spelling doaj.art-5420a62bdf7f4e82bb27a90624e42df32023-11-30T22:34:37ZengMDPI AGSymmetry2073-89942022-02-0114343710.3390/sym14030437Stable Calculation of Discrete Hahn FunctionsAlbertus C. den Brinker0Philips Research, 5656 AE Eindhoven, The NetherlandsGenerating discrete orthogonal polynomials from the recurrence or difference equation is error-prone, as it is sensitive to error propagation and dependent on highly accurate initial values. Strategies to handle this, involving control over the deviation of norm and orthogonality, have already been developed for the discrete Chebyshev and Krawtchouk functions, i.e., the orthonormal basis in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mn>2</mn></msub></semantics></math></inline-formula> derived from the polynomials. Since these functions are limiting cases of the discrete Hahn functions, it suggests that the strategy could also be successful there. We outline the algorithmic strategies including the specific method of generating the initial values, and show that the orthonormal basis can indeed be generated for large supports and polynomial degrees with controlled numerical error. Special attention is devoted to symmetries, as the symmetric windows are most commonly used in signal processing, allowing for simplification of the algorithm due to this prior knowledge, and leading to savings in the required computational power.https://www.mdpi.com/2073-8994/14/3/437orthogonal polynomialsdiscrete Hahn polynomialsdiscrete Hahn functionserror propagationdifference equationthree-term recurrence relation
spellingShingle Albertus C. den Brinker
Stable Calculation of Discrete Hahn Functions
Symmetry
orthogonal polynomials
discrete Hahn polynomials
discrete Hahn functions
error propagation
difference equation
three-term recurrence relation
title Stable Calculation of Discrete Hahn Functions
title_full Stable Calculation of Discrete Hahn Functions
title_fullStr Stable Calculation of Discrete Hahn Functions
title_full_unstemmed Stable Calculation of Discrete Hahn Functions
title_short Stable Calculation of Discrete Hahn Functions
title_sort stable calculation of discrete hahn functions
topic orthogonal polynomials
discrete Hahn polynomials
discrete Hahn functions
error propagation
difference equation
three-term recurrence relation
url https://www.mdpi.com/2073-8994/14/3/437
work_keys_str_mv AT albertuscdenbrinker stablecalculationofdiscretehahnfunctions