<p>Logarithmic coefficients play a crucial role in the theory of univalent functions. In this study, we focus on the classes <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\({\mathcal {S}}_e^*\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi mathvariant="script">S</mi> <mi>e</mi> <mo>∗</mo> </msubsup> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\({\mathcal {C}}_e\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">C</mi> <mi>e</mi> </msub> </math></EquationSource> </InlineEquation> of starlike and convex functions, respectively, <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\( {\mathcal {S}}_e^*{:}{=} \left\{ f \in {\mathcal {S}} : \frac{zf'(z)}{f(z)} \prec e^z, \ z \in \mathbb {D} \right\} ,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msubsup> <mi mathvariant="script">S</mi> <mi>e</mi> <mo>∗</mo> </msubsup> <mo>:</mo> <mo>=</mo> <mfenced close="}" open="{"> <mi>f</mi> <mo>∈</mo> <mi mathvariant="script">S</mi> <mo>:</mo> <mfrac> <mrow> <mi>z</mi> <msup> <mi>f</mi> <mo>′</mo> </msup> <mrow> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> </mrow> <mrow> <mi>f</mi> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> </mfrac> <mo>≺</mo> <msup> <mi>e</mi> <mi>z</mi> </msup> <mo>,</mo> <mspace width="4pt" /> <mi>z</mi> <mo>∈</mo> <mi mathvariant="double-struck">D</mi> </mfenced> <mo>,</mo> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\( \mathcal {C}_e {:}{=} \left\{ f \in \mathcal {S} : 1 + \frac{z f''(z)}{f'(z)} \prec e^z, \ z \in \mathbb {D} \right\} .\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="script">C</mi> <mi>e</mi> </msub> <mo>:</mo> <mo>=</mo> <mfenced close="}" open="{"> <mi>f</mi> <mo>∈</mo> <mi mathvariant="script">S</mi> <mo>:</mo> <mn>1</mn> <mo>+</mo> <mfrac> <mrow> <mi>z</mi> <msup> <mi>f</mi> <mrow> <mo>′</mo> <mo>′</mo> </mrow> </msup> <mrow> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> </mrow> <mrow> <msup> <mi>f</mi> <mo>′</mo> </msup> <mrow> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </mfrac> <mo>≺</mo> <msup> <mi>e</mi> <mi>z</mi> </msup> <mo>,</mo> <mspace width="4pt" /> <mi>z</mi> <mo>∈</mo> <mi mathvariant="double-struck">D</mi> </mfenced> <mo>.</mo> </mrow> </math></EquationSource> </InlineEquation> This paper investigates the sharp bounds of the logarithmic coefficients and the Hermitian-Toeplitz determinant of these coefficients for the classes <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(\mathcal {S}_e^*\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi mathvariant="script">S</mi> <mi>e</mi> <mo>∗</mo> </msubsup> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\mathcal {C}_e\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">C</mi> <mi>e</mi> </msub> </math></EquationSource> </InlineEquation>. Additionally, we examine the generalized Zalcman conjecture and the generalized Fek ete-Szegö inequality for these classes <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(\mathcal {S}_e^*\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi mathvariant="script">S</mi> <mi>e</mi> <mo>∗</mo> </msubsup> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(\mathcal {C}_e\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">C</mi> <mi>e</mi> </msub> </math></EquationSource> </InlineEquation> and show that the inequalities are sharp.</p>

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On coefficient problems for classes \(\mathcal {S}_{e}^{*}\) and \(\mathcal {C}_e\)

  • Sujoy Majumder,
  • Nabadwip Sarkar,
  • Molla Basir Ahamed

摘要

Logarithmic coefficients play a crucial role in the theory of univalent functions. In this study, we focus on the classes \({\mathcal {S}}_e^*\) S e and \({\mathcal {C}}_e\) C e of starlike and convex functions, respectively, \( {\mathcal {S}}_e^*{:}{=} \left\{ f \in {\mathcal {S}} : \frac{zf'(z)}{f(z)} \prec e^z, \ z \in \mathbb {D} \right\} ,\) S e : = f S : z f ( z ) f ( z ) e z , z D , and \( \mathcal {C}_e {:}{=} \left\{ f \in \mathcal {S} : 1 + \frac{z f''(z)}{f'(z)} \prec e^z, \ z \in \mathbb {D} \right\} .\) C e : = f S : 1 + z f ( z ) f ( z ) e z , z D . This paper investigates the sharp bounds of the logarithmic coefficients and the Hermitian-Toeplitz determinant of these coefficients for the classes \(\mathcal {S}_e^*\) S e and \(\mathcal {C}_e\) C e . Additionally, we examine the generalized Zalcman conjecture and the generalized Fek ete-Szegö inequality for these classes \(\mathcal {S}_e^*\) S e and \(\mathcal {C}_e\) C e and show that the inequalities are sharp.