Partial sums and inclusion relations for analytic functions involving (p, q)-differential operator

Let fk(z)=z+∑n=2kanzn{f}_{k}\left(z)=z+{\sum }_{n=2}^{k}{a}_{n}{z}^{n} be the sequence of partial sums of the analytic function f(z)=z+∑n=2∞anznf\left(z)=z+{\sum }_{n=2}^{\infty }{a}_{n}{z}^{n}. In this paper, we determine sharp lower bounds for Re{f(z)/fk(z)}{\rm{Re}}\{f\left(z)\hspace{-0.08em}\tex...

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Autores principales: Tang Huo, Vijaya Kaliappan, Murugusundaramoorthy Gangadharan, Sivasubramanian Srikandan
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Publicado: De Gruyter 2021
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spelling oai:doaj.org-article:5e4a1d6bcd1a43eb8bd7d9e85a3795b12021-12-05T14:10:52ZPartial sums and inclusion relations for analytic functions involving (p, q)-differential operator2391-545510.1515/math-2021-0028https://doaj.org/article/5e4a1d6bcd1a43eb8bd7d9e85a3795b12021-05-01T00:00:00Zhttps://doi.org/10.1515/math-2021-0028https://doaj.org/toc/2391-5455Let fk(z)=z+∑n=2kanzn{f}_{k}\left(z)=z+{\sum }_{n=2}^{k}{a}_{n}{z}^{n} be the sequence of partial sums of the analytic function f(z)=z+∑n=2∞anznf\left(z)=z+{\sum }_{n=2}^{\infty }{a}_{n}{z}^{n}. In this paper, we determine sharp lower bounds for Re{f(z)/fk(z)}{\rm{Re}}\{f\left(z)\hspace{-0.08em}\text{/}\hspace{-0.08em}{f}_{k}\left(z)\}, Re{fk(z)/f(z)}{\rm{Re}}\{{f}_{k}\left(z)\hspace{-0.08em}\text{/}\hspace{-0.08em}f\left(z)\}, Re{f′(z)/fk′(z)}{\rm{Re}}\{{f}^{^{\prime} }\left(z)\hspace{-0.08em}\text{/}\hspace{-0.08em}{f}_{k}^{^{\prime} }\left(z)\} and Re{fk′(z)/f′(z)}{\rm{Re}}\{{f}_{k}^{^{\prime} }\left(z)\hspace{-0.08em}\text{/}\hspace{-0.08em}{f}^{^{\prime} }\left(z)\}, where f(z)f\left(z) belongs to the subclass Jp,qm(μ,α,β){{\mathcal{J}}}_{p,q}^{m}\left(\mu ,\alpha ,\beta ) of analytic functions, defined by Sălăgean (p,q)\left(p,q)-differential operator. In addition, the inclusion relations involving Nδ(e){N}_{\delta }\left(e) of this generalized function class are considered.Tang HuoVijaya KaliappanMurugusundaramoorthy GangadharanSivasubramanian SrikandanDe Gruyterarticleanalyticunivalent(p, q)-differential operatorpartial suminclusion relation30c4530c50MathematicsQA1-939ENOpen Mathematics, Vol 19, Iss 1, Pp 329-337 (2021)
institution DOAJ
collection DOAJ
language EN
topic analytic
univalent
(p, q)-differential operator
partial sum
inclusion relation
30c45
30c50
Mathematics
QA1-939
spellingShingle analytic
univalent
(p, q)-differential operator
partial sum
inclusion relation
30c45
30c50
Mathematics
QA1-939
Tang Huo
Vijaya Kaliappan
Murugusundaramoorthy Gangadharan
Sivasubramanian Srikandan
Partial sums and inclusion relations for analytic functions involving (p, q)-differential operator
description Let fk(z)=z+∑n=2kanzn{f}_{k}\left(z)=z+{\sum }_{n=2}^{k}{a}_{n}{z}^{n} be the sequence of partial sums of the analytic function f(z)=z+∑n=2∞anznf\left(z)=z+{\sum }_{n=2}^{\infty }{a}_{n}{z}^{n}. In this paper, we determine sharp lower bounds for Re{f(z)/fk(z)}{\rm{Re}}\{f\left(z)\hspace{-0.08em}\text{/}\hspace{-0.08em}{f}_{k}\left(z)\}, Re{fk(z)/f(z)}{\rm{Re}}\{{f}_{k}\left(z)\hspace{-0.08em}\text{/}\hspace{-0.08em}f\left(z)\}, Re{f′(z)/fk′(z)}{\rm{Re}}\{{f}^{^{\prime} }\left(z)\hspace{-0.08em}\text{/}\hspace{-0.08em}{f}_{k}^{^{\prime} }\left(z)\} and Re{fk′(z)/f′(z)}{\rm{Re}}\{{f}_{k}^{^{\prime} }\left(z)\hspace{-0.08em}\text{/}\hspace{-0.08em}{f}^{^{\prime} }\left(z)\}, where f(z)f\left(z) belongs to the subclass Jp,qm(μ,α,β){{\mathcal{J}}}_{p,q}^{m}\left(\mu ,\alpha ,\beta ) of analytic functions, defined by Sălăgean (p,q)\left(p,q)-differential operator. In addition, the inclusion relations involving Nδ(e){N}_{\delta }\left(e) of this generalized function class are considered.
format article
author Tang Huo
Vijaya Kaliappan
Murugusundaramoorthy Gangadharan
Sivasubramanian Srikandan
author_facet Tang Huo
Vijaya Kaliappan
Murugusundaramoorthy Gangadharan
Sivasubramanian Srikandan
author_sort Tang Huo
title Partial sums and inclusion relations for analytic functions involving (p, q)-differential operator
title_short Partial sums and inclusion relations for analytic functions involving (p, q)-differential operator
title_full Partial sums and inclusion relations for analytic functions involving (p, q)-differential operator
title_fullStr Partial sums and inclusion relations for analytic functions involving (p, q)-differential operator
title_full_unstemmed Partial sums and inclusion relations for analytic functions involving (p, q)-differential operator
title_sort partial sums and inclusion relations for analytic functions involving (p, q)-differential operator
publisher De Gruyter
publishDate 2021
url https://doaj.org/article/5e4a1d6bcd1a43eb8bd7d9e85a3795b1
work_keys_str_mv AT tanghuo partialsumsandinclusionrelationsforanalyticfunctionsinvolvingpqdifferentialoperator
AT vijayakaliappan partialsumsandinclusionrelationsforanalyticfunctionsinvolvingpqdifferentialoperator
AT murugusundaramoorthygangadharan partialsumsandinclusionrelationsforanalyticfunctionsinvolvingpqdifferentialoperator
AT sivasubramaniansrikandan partialsumsandinclusionrelationsforanalyticfunctionsinvolvingpqdifferentialoperator
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