Inclusion properties for a class of analytic functions defined by a second-order differential inequality
For β < 1 , and α ≥ γ ≥ 0 , let W β ( α , γ ) consist of normalized analytic functions f in the unit disk satisfying Re e i ϕ ( 1 - α + 2 γ ) f ( z ) / z + ( α - 2 γ ) f ′ ( z ) + γ z f ′ ′ ( z ) - β > 0 , z ∈ D , for some ϕ with | ϕ | < π / 2 . The extreme points and sharp coefficient boun...
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Veröffentlicht in: | Revista de la Real Academia de Ciencias Exactas, Físicas y Naturales. Serie A, Matemáticas Físicas y Naturales. Serie A, Matemáticas, 2018, Vol.112 (1), p.117-133 |
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Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
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Zusammenfassung: | For
β
<
1
, and
α
≥
γ
≥
0
,
let
W
β
(
α
,
γ
)
consist of normalized analytic functions
f
in the unit disk satisfying
Re
e
i
ϕ
(
1
-
α
+
2
γ
)
f
(
z
)
/
z
+
(
α
-
2
γ
)
f
′
(
z
)
+
γ
z
f
′
′
(
z
)
-
β
>
0
,
z
∈
D
,
for some
ϕ
with
|
ϕ
|
<
π
/
2
. The extreme points and sharp coefficient bounds for this class are determined. Estimates on
β
are also found that would ensure functions in
W
β
(
α
,
γ
)
are starlike. When
β
=
0
, a sharp radius of univalence is obtained for the class
W
0
(
α
,
γ
)
. Additionally sufficient conditions in terms of the Schwarzian derivative and the second Taylor coefficient are obtained for functions
f
to belong to the class
W
0
(
α
,
γ
)
. |
---|---|
ISSN: | 1578-7303 1579-1505 |
DOI: | 10.1007/s13398-016-0368-1 |