<p>Let <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13370_2025_1372_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="37" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {G}}(\alpha )\)</EquationSource> </InlineEquation> denote the family of functions <i>f</i>(<i>z</i>) in the open unit disk <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13370_2025_1372_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="163" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathbb {D}} :=\{z\in {\mathbb {C}}: |z|&lt;1\}\)</EquationSource> </InlineEquation> that satisfy <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13370_2025_1372_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="149" /> </InlineMediaObject> <EquationSource Format="TEX">\(f(0)=0=f'(0)=1\)</EquationSource> </InlineEquation> and <Equation ID="Equ43"> <MediaObject> <ImageObject Color="BlackWhite" FileRef="13370_2025_1372_Article_Equ43.gif" Format="GIF" Height="43" Rendition="HTML" Resolution="72" Type="Linedraw" Width="253" /> </MediaObject> <EquationSource Format="TEX">\(\begin{aligned} \Re \left( 1+ \dfrac{zf''(z)}{f'(z)}\right) &lt;1+\dfrac{\alpha }{2} , \quad z\in {\mathbb {D}}. \end{aligned}\)</EquationSource> </Equation>We determine the disks <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13370_2025_1372_Article_IEq4.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="61" /> </InlineMediaObject> <EquationSource Format="TEX">\(|z|&lt;\rho _n\)</EquationSource> </InlineEquation> in which sections <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13370_2025_1372_Article_IEq5.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="55" /> </InlineMediaObject> <EquationSource Format="TEX">\(s_n(z;f)\)</EquationSource> </InlineEquation> of <i>f</i>(<i>z</i>) are convex, starlike, and close-to-convex of order <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13370_2025_1372_Article_IEq6.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="102" /> </InlineMediaObject> <EquationSource Format="TEX">\(\beta \;(0\le \beta &lt; 1)\)</EquationSource> </InlineEquation>. Further, we obtain certain inequalities of sections in the considered class of functions.</p>

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Radii for sections of functions convex in one direction

  • Prachi Prajna Dash,
  • Jugal Kishore Prajapat,
  • Naveen Kumari

摘要

Let \({\mathcal {G}}(\alpha )\) denote the family of functions f(z) in the open unit disk \({\mathbb {D}} :=\{z\in {\mathbb {C}}: |z|<1\}\) that satisfy \(f(0)=0=f'(0)=1\) and \(\begin{aligned} \Re \left( 1+ \dfrac{zf''(z)}{f'(z)}\right) <1+\dfrac{\alpha }{2} , \quad z\in {\mathbb {D}}. \end{aligned}\) We determine the disks \(|z|<\rho _n\) in which sections \(s_n(z;f)\) of f(z) are convex, starlike, and close-to-convex of order \(\beta \;(0\le \beta < 1)\) . Further, we obtain certain inequalities of sections in the considered class of functions.