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Further results for a subclass of univalent functions related with differential inequality

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Abstract

Let \(\Omega\) denote the class of functions f analytic in the open unit disc \(\Delta\), normalized by the condition \(f(0)=f'(0)-1=0\) and satisfying the inequality

$$\begin{aligned} \left| zf'(z)-f(z)\right| <\frac{1}{2}\quad (z\in \Delta ). \end{aligned}$$

The class \(\Omega\) was introduced recently by Peng and Zhong (Acta Math Sci 37B(1):69–78, 2017). Also let \({\mathcal {U}}\) denote the class of functions f analytic and normalized in \(\Delta\) and satisfying the condition

$$\begin{aligned} \left| \left( \frac{z}{f(z)}\right) ^2f'(z)-1\right| <1\quad (z\in \Delta ). \end{aligned}$$

In this article, we obtain some further results for the class \(\Omega\) including, an extremal function and more examples of \(\Omega\), inclusion relation between \(\Omega\) and \({\mathcal {U}}\), the radius of starlikeness, convexity and close–to–convexity and sufficient condition for function f to be in \(\Omega\). Furthermore, along with the settlement of the coefficient problem and the Fekete–Szegö problem for the elements of \(\Omega\), the Toeplitz matrices for \(\Omega\) are also discussed in this article.

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Acknowledgements

We thank the anonymous reviewer for his/her careful reading of our manuscript and his/her comments and suggestions.

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Correspondence to Rahim Kargar.

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Communicated by Kaushal Verma.

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Mahzoon, H., Kargar, R. Further results for a subclass of univalent functions related with differential inequality. Indian J Pure Appl Math 52, 205–215 (2021). https://doi.org/10.1007/s13226-021-00071-2

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