共查询到20条相似文献,搜索用时 15 毫秒
1.
Zygmund函数在闭区间上最大值的估计 总被引:1,自引:0,他引:1
对任意实数集 R上的 Zygmund函数 f(x) ,满足条件 :|f(x+t) - 2 f(x) +f(x- t) | ‖ f‖z|t|,x,t∈ R ,且 f(0 ) =f (1 ) =0 ,本文证明maxx∈ [0 ,1 ] |f(x) | 13‖ f‖z. 相似文献
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A real-valued function f(x) on Ж belongs to Zygmund class A.(Ж) ff its Zygmund norm ‖f‖x=inf,|f(x+t)-2f(x)+f(x-t)/t|is finite. It is proved that when f∈A*(Ж), there exists an extension F(z) of f to H={Imz>0} such that ‖Э^-F‖∞≤√—1+53^2/72‖f‖z.It is also proved that if f(0)=f(1)=0, thenmax,x∈[0,1]|f(x)|≤1/3‖f‖x. 相似文献
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《数学研究与评论》1991,(4)
Let H(D)be the collection of functions which are analytic in the unitdisc D.we call B_0={f∈H(D),(?)(1-|z|~2)|f’(z)|=0}litlle Bloch space.Letf∈H(D),0
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设f(z)=Z+a_2z~2+…∈S.Szeg证明:S_n(z)=z+a_2z~2+…+a_nz~n(n=2,3…)在|z|<1/4内单叶。ρ_O=1/4最好的,我们证明了更强的结果: 定理:若f(z)∈s.则s_n(z)(n=2,3…)在|z|<1/4内关于原点成星形。 当f∈S时为吴卓人所得。 相似文献
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本文主要研究了Cn单位球上Hilbert值Dμ,q函数的收敛性,得到了若f=∑α≥0xαzα∈Dμ,q,q>(2n)/(μ),则φ(z)=∑α≥0‖xα‖zα∈Lipγ,其中0<μ<1(n=1)或0<μ<2(n>1).此外还得到若f∈Dμ,q,q>(2n)/(μ),则对几乎所有的{εα}有fω(z)∈H∞,其中0<μ<1(n=1)或0<μ<2(n>1).在此过程中,我们利用了Banach空间几何学和Rademacher函数序列的知识. 相似文献
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研究了解析函数与Lipschitz条件,得到了如下两个结果:(i)设D是一平面区域,f(z)在D中解析,00,对任意z∈D有|f′(z)|≤md(z,D)k-1,则f∈Lipk(D)且‖f‖k≤cmk,其中c=c(D)是仅与D有关的常数. 相似文献
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Bers型空间和复合算子 总被引:6,自引:0,他引:6
For α∈(0,∞),let Hα^∞(or Hα^∞,0)denote the collection of all functions f which are analytic on the unit disc D and satisfy |f(z)|(1-|z|^2)^α=O(1)(or|f(z)|(1-|z|^2)^α=o(1) as |z|→1).Hα^∞,0)is called a Bers-type space (or a little Bers-type space).In this paper,we give some basic properties of Hα^∞,Cψ,the composition operator associated with a symbol function ψ which is an analytic self map of D,is difined by Cψf=f o ψ,We characterize the boundedness,and compactness of Cψ which sends one Bers-type space to another function space. 相似文献
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设Ω={f(z):f(z)在|z|<1内解析,f(z)=z+∑^{+∞}_{n=2}{a_n z^n}, a_n是实数,∑^{+∞}_{n=2}{n|a_n|≤1}}.该文找出了函数族Ω的极值点与支撑点.
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10.
DongshengLiu 《工科数学》1999,15(1):70-75
In this paper, we characterize BMOA and VMOA on the unit ball in terms of normsNp(f)=sup/x∈B{1/σ(Q(z))∫Q(z)│f(ξ)-f(z)│pdσ(ξ)}^1/p,1≤p&;lt;∞ and more general Garcia norms.Where Q(z)=Q(n(z),δz)={ξ∈S,│^1/2&;lt;δZ}.n(z)={e1,z=0,/z/│z│,z=0,δz=[2(1-│z│)]^1/2. 相似文献
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The generalized Roper-Suffridge extension operator Ф(f) on the bounded complete Reinhardt domain Ω in Cn with n ≥ 2 is defined by Φrn,β2,γ2,…,βn,γn(f)(z)=(rf(z1/r),(rf(z1/r)/z1)β2(f'(z1/r))γ2z2,…,(rf(z1/r)/z1)βn(f'(z1/r)γnzn) for (z1,z2,…,zn) ∈Ω, where r = r(Ω) = sup{|z1| (z1,z2,…,zn) ∈ Ω},0 ≤ γj ≤ 1 -βj,0 ≤ βj ≤ 1,and we choose the branch of the power functions such that (f(z1)/z1)βj |z1=0 = 1 and (f′(z1))γj |z1=0 =1,j = 2,…,n. In this paper, we prove that the operator Фrn,β2,γ2,…,βn,γn(f) is from the subset of S*α(U) to S*α(Ω)(0 ≤ α < 1) on Ω and the operator Фrn,β2,γ2,…, βn,γn(f) preserves the starlikeness of order α or the spirallikeness of type β on Dp for some suitable constantsβj,γj,pj, where Dp ={(z1,z2,…,zn) ∈ Cn ∑nj=1|zj|pj < 1} (pj > 0, j = 1,2,…,n), U is the unit disc in the complex plane C, and Sα* (Ω) is the class of all normalized starlike mappings of order α on Ω. We also obtain that Φrn,β2,γ2,…,γn(f) ∈ S*α(Dp) if and only if f ∈ S*a(U) for 0 ≤ α < 1 and some suitable constants βj,γj,pj. 相似文献
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关于Szász-Mirakjan算子 总被引:1,自引:0,他引:1
§1 前言设 C={f∶f∈C[0,∞),存在着 N>0,使得 f(x)=O(x~N)(x→ ∞)}.C~r={f;f~(t)∈C.i=0,1,2,…,r}.Szász-Mirakjan 算子是:S_n(,fx)=(?)f(k/n)P_(nk)(x),P_(nk)(x)=e~(-nx)((nx)~k)/(k!),f∈C设 C_0={f:f∈C[0,∞),(?)(?)类似地定义 C_0~r.在[1]中我们曾证明了:对于C_0 中的函数 f,‖S_n(f)-f‖_c=O(k(f,(?)).若0<α<1,则‖S_n(f)-f‖_e=O(n~(-α)与k(f,t)=O(t~(2α))等价。这里 k(f,t)=inf{‖f-g‖_c t~2‖xg〃‖c‖}.不难类似地证明此结 相似文献
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Suppose f is an almost starlike function of order α on the unit disk D. In this paper, we will prove that Φn, β2, γ2, …, βn, γn (f)(z) = (f(z1), (f(z1)/z1)β2(f'(z1))γ2z2,…,(f(z1)/z1)βn(f'(z11))γnzn)' preserves almost starlikeness of order α on Ωn,p1,p2,…,pn = {z =(z1,z2,…,zn)' ∈ Cn n∑j=1 |zj|pj < 1}, where 0 < p11 ≤ 2, pj ≥ 1, j = 2,…,n, are real numbers. 相似文献
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设z为复数,且|z|=1,对于实系数复多项式为h(z)=h0 h1z h2z2 … hnzn,h0·hn≠0,为求|h(z)|max与|h(z)|min,令f(z)=h(z)h(z-1)=r0 nj=1 rj (zj z-j),其中r0=nk=0 h2k,rj=nk=0 hk·hk j (hk=0,k>n时),由|z|=1可设z=cosθ isinθ,θ∈[0,2π],由欧拉公式知z=eiθ.于是有|h(z)|=h(eiθ)=|h(eiθ)·h(e-iθ)|12=|f(eiθ)|12=|f(z)|12,所以f(z)=f(eiθ)=r0 nj=1 rj(eijθ e-ijθ)=r0 nj=1 2rjcosjθ,其中cosjθ可表示成cosθ的函数,因此f(eiθ)也可表示成cosθ的一元函数,即f(eiθ)=r0 2r1cos… 相似文献
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Let A be the space of functions analytic in the unit disk D = {z:|z| 1}.Let U denote the set of all functions f ∈ A satisfying the conditions f(0) = f'(0)-1 = 0 and|f'(z)(z/f(z))~2-1|1(|z|1).Also,let Ω denote the set of all functions f ∈ A satisfying the conditions f(0) = f'(0)-1 = 0and|zf'(z)-f(z)|1/2(|z|1).In this article,we discuss the properties of U and Ω. 相似文献
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Bohr's type inequalities are studied in this paper: if f is a holomorphic mapping from the unit ball B~n to B~n, f(0)=p, then we have sum from k=0 to∞|Dφ_P(P)[D~kf(0)(z~k)]|/k!||Dφ_P(P)||<1 for|z|<max{1/2 |P|,(1-|p|)/2~(1/2)andφ_P∈Aut(B~n) such thatφ_(p)=0. As corollaries of the above estimate, we obtain some sharp Bohr's type modulus inequalities. In particular, when n=1 and |P|→1, then our theorem reduces to a classical result of Bohr. 相似文献
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李立康 《数学年刊A辑(中文版)》1985,(4)
本文用有限元法得到非线性Dirichlet问题的近似解。有限元空间V_h定义如下: V_h={v_h|v_h∈C~0(Ω),在每一个K_i上v_h是线性函数},这里{K_i}是Ω的一个剖分,h=max(diam(K_i))。用A_1,…,A_n 表示所有边界结点。定义 V_h~g={v_h|v_h∈V_h,v_h(A_i)=g(A_i)(i=1,…,n)}, V_h~0={v_h|v_h∈V_h,v_h(A_i)=0(i=1,…,n)}。 变分问题:找一个u_~*∈V_h~g使满足 (a(x,u_h~*)?u_h~*,?u_h~)=(f,v_h),?v_h∈V_h~0。 在一定条件下,成立 ‖u-u_h~*‖_0+h‖u-u_h~*‖_1≤Ch~2。 相似文献
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正实部解折函数的渐近性质 总被引:1,自引:0,他引:1
一 引言 令表示P(z)在U:|z|<1内正则P(0)=1,且ReP(z)>0的函数全体。中两函数P_1,P_2的Hadamard乘积定义为 (P_1*P_2)(z)=1+1/2sum from n=1 to ∞(C_n~(1)C_n~(2)z~n) 其中 P_i(z)=1+sum from n=1 to ∞(C_n~(i)z~n∈记P(z)=1+sum from n=1 to ∞C_nz~n。 本文主要研究P(z)的渐近性质,最后说明其在单时函数论中的应用。二 几条引理 相似文献