Let
H(U) be the space of analytic functions in the unit disk U and let \mathscr{D}={φ∈
H(U):φ(0)=1, φ(
z)≠0,
z∈U}. For the functions φ, φ∈\mathscr{D} we will determine simple sufficient conditions such that
[\frac{φ(
z)}{φ(
z)+(1/γ)
zφ'(
z)}]
1/βf(
z) {\prec}
k(
z){⇒}
Iφ, φ;β, γ[
f](
z) {\prec}
k(
z),
for all
k∈\mathscr{M}
1/β', where
Iφ, φ;β, γ[
f](
z)=[\frac{γ}{
zγφ(
z)}∫
0zfβ(
t)
tγ−1φ(
t) d
t]
1/βand \mathscr{M}
1/β' represents the class of 1/β-convex functions (not necessarily normalized).
In particular, we will give sufficient conditions on φ and φ so that the operators
Iφ, φ;β, γ are averaging operators on certain subsets of
H(U). In addition, some particular cases of the main result, obtained for appropriate choices of the φ and φ functions, will also be given.
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