On Certain Bounds of Harmonic Univalent Functions

Harmonic functions are renowned for their application in the analysis of minimal surfaces. These functions are also very important in applied mathematics. Any harmonic function in the open unit disk <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inl...

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Main Authors: Fethiye Müge Sakar, Omendra Mishra, Georgia Irina Oros, Basem Aref Frasin
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Axioms
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Online Access:https://www.mdpi.com/2075-1680/14/6/393
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author Fethiye Müge Sakar
Omendra Mishra
Georgia Irina Oros
Basem Aref Frasin
author_facet Fethiye Müge Sakar
Omendra Mishra
Georgia Irina Oros
Basem Aref Frasin
author_sort Fethiye Müge Sakar
collection DOAJ
description Harmonic functions are renowned for their application in the analysis of minimal surfaces. These functions are also very important in applied mathematics. Any harmonic function in the open unit disk <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="double-struck">U</mi><mo>=</mo><mfenced separators="" open="{" close="}"><mi>z</mi><mo>∈</mo><mi mathvariant="double-struck">C</mi><mo>:</mo><mfenced open="|" close="|"><mi>z</mi></mfenced><mo><</mo><mn>1</mn></mfenced></mrow></semantics></math></inline-formula> can be written as a sum <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>=</mo><mi>h</mi><mo>+</mo><mover><mi>g</mi><mo>¯</mo></mover></mrow></semantics></math></inline-formula>, where <i>h</i> and <i>g</i> are analytic functions in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="double-struck">U</mi></semantics></math></inline-formula> and are called the analytic part and the co-analytic part of <i>f</i>, respectively. In this paper, the harmonic shear <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>=</mo><mi>h</mi><mo>+</mo><mover><mi>g</mi><mo>¯</mo></mover><mo>∈</mo><msub><mi>S</mi><mi mathvariant="script">H</mi></msub></mrow></semantics></math></inline-formula> and its rotation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>f</mi><mi>μ</mi></msup></semantics></math></inline-formula> by <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>μ</mi><mspace width="4pt"></mspace><mfenced separators="" open="(" close=")"><mi>μ</mi><mo>∈</mo><mi mathvariant="double-struck">C</mi><mo>,</mo><mfenced open="|" close="|"><mi>μ</mi></mfenced><mo>=</mo><mn>1</mn></mfenced></mrow></semantics></math></inline-formula> are considered. Bounds are established for this rotation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>f</mi><mi>μ</mi></msup></semantics></math></inline-formula>, specific inequalities that define the Jacobian of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>f</mi><mi>μ</mi></msup></semantics></math></inline-formula> are obtained, and the integral representation is determined.
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spelling doaj-art-463a13da4c2846f2beb8b13a0cb02e122025-08-20T03:32:31ZengMDPI AGAxioms2075-16802025-05-0114639310.3390/axioms14060393On Certain Bounds of Harmonic Univalent FunctionsFethiye Müge Sakar0Omendra Mishra1Georgia Irina Oros2Basem Aref Frasin3Department of Management, Dicle University, Diyarbakir 21280, TurkeyDepartment of Mathematical and Statistical Sciences, Institute of Natural Sciences and Humanities, Shri Ramswaroop Memorial University, Lucknow 225003, IndiaDepartment of Mathematics and Computer Science, University of Oradea, 410087 Oradea, RomaniaDepartment of Mathematics, Faculty of Science, Al al-Bayt University, Mafraq 25113, JordanHarmonic functions are renowned for their application in the analysis of minimal surfaces. These functions are also very important in applied mathematics. Any harmonic function in the open unit disk <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="double-struck">U</mi><mo>=</mo><mfenced separators="" open="{" close="}"><mi>z</mi><mo>∈</mo><mi mathvariant="double-struck">C</mi><mo>:</mo><mfenced open="|" close="|"><mi>z</mi></mfenced><mo><</mo><mn>1</mn></mfenced></mrow></semantics></math></inline-formula> can be written as a sum <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>=</mo><mi>h</mi><mo>+</mo><mover><mi>g</mi><mo>¯</mo></mover></mrow></semantics></math></inline-formula>, where <i>h</i> and <i>g</i> are analytic functions in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="double-struck">U</mi></semantics></math></inline-formula> and are called the analytic part and the co-analytic part of <i>f</i>, respectively. In this paper, the harmonic shear <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>=</mo><mi>h</mi><mo>+</mo><mover><mi>g</mi><mo>¯</mo></mover><mo>∈</mo><msub><mi>S</mi><mi mathvariant="script">H</mi></msub></mrow></semantics></math></inline-formula> and its rotation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>f</mi><mi>μ</mi></msup></semantics></math></inline-formula> by <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>μ</mi><mspace width="4pt"></mspace><mfenced separators="" open="(" close=")"><mi>μ</mi><mo>∈</mo><mi mathvariant="double-struck">C</mi><mo>,</mo><mfenced open="|" close="|"><mi>μ</mi></mfenced><mo>=</mo><mn>1</mn></mfenced></mrow></semantics></math></inline-formula> are considered. Bounds are established for this rotation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>f</mi><mi>μ</mi></msup></semantics></math></inline-formula>, specific inequalities that define the Jacobian of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>f</mi><mi>μ</mi></msup></semantics></math></inline-formula> are obtained, and the integral representation is determined.https://www.mdpi.com/2075-1680/14/6/393univalent harmonic functionshear constructionconvex functionconvexity in a directiongrowth and distortion bounds
spellingShingle Fethiye Müge Sakar
Omendra Mishra
Georgia Irina Oros
Basem Aref Frasin
On Certain Bounds of Harmonic Univalent Functions
Axioms
univalent harmonic function
shear construction
convex function
convexity in a direction
growth and distortion bounds
title On Certain Bounds of Harmonic Univalent Functions
title_full On Certain Bounds of Harmonic Univalent Functions
title_fullStr On Certain Bounds of Harmonic Univalent Functions
title_full_unstemmed On Certain Bounds of Harmonic Univalent Functions
title_short On Certain Bounds of Harmonic Univalent Functions
title_sort on certain bounds of harmonic univalent functions
topic univalent harmonic function
shear construction
convex function
convexity in a direction
growth and distortion bounds
url https://www.mdpi.com/2075-1680/14/6/393
work_keys_str_mv AT fethiyemugesakar oncertainboundsofharmonicunivalentfunctions
AT omendramishra oncertainboundsofharmonicunivalentfunctions
AT georgiairinaoros oncertainboundsofharmonicunivalentfunctions
AT basemareffrasin oncertainboundsofharmonicunivalentfunctions