On an extension of Nunokawa’s lemma
Jack’s Lemma says that if f ( z ) is regular in the disc | z | ≤ r , f ( 0 ) = 0 , and | f ( z )| assumes its maximum at z 0 on the circle | z | = r , then z 0 f ′ ( z ) 0 / f ( z 0 ) ≥ 1 . This Lemma was generalized in several directions. In this paper we consider an improvement of some first autho...
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| Veröffentlicht in: | Analysis and mathematical physics 2022-02, Vol.12 (1), Article 36 |
|---|---|
| Hauptverfasser: | , |
| Format: | Artikel |
| Sprache: | eng |
| Schlagworte: | |
| Online-Zugang: | Volltext |
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| Zusammenfassung: | Jack’s Lemma says that if
f
(
z
) is regular in the disc
|
z
|
≤
r
,
f
(
0
)
=
0
, and |
f
(
z
)| assumes its maximum at
z
0
on the circle
|
z
|
=
r
, then
z
0
f
′
(
z
)
0
/
f
(
z
0
)
≥
1
. This Lemma was generalized in several directions. In this paper we consider an improvement of some first author’s results of this type. |
|---|---|
| ISSN: | 1664-2368 1664-235X |
| DOI: | 10.1007/s13324-021-00598-x |