共查询到20条相似文献,搜索用时 171 毫秒
1.
刘卫国 《高等学校计算数学学报》1997,19(2):173-183
所求的解就是c在p上的投影。 对于问题(1.1),He基于求解线性互补问题的投影收缩(PC)法,把投影问题转化为等价的广义线性互补问题,提出了一个求解这类问题的迭代方法。 原始的PC方法只能证明迭代是全局收敛的,而无法估计其收敛速度。为此,[4]和[5]对原始的PC方法作了改进,提出了固定步长的PC法并证明了其收敛速度是线性的。但在实际应用中,固定步长的PC法比原始的PC法慢的多,而且在求步长时,还要估计约束矩阵范数的大小。 本文基于[5]的思想,对于(1.1)提出了一个新的PC方法,该方法是全局线性收敛的。 本文中用到的符号说明如下:x_i表示x的第i个分量。如果u∈(?)且Ω(?)(?)为凸闭集,则P_Ω[u]定义为u到Ω上的投影。特别地,u_+定义为u到非负卦限(?)上的投影,对于一个正定矩阵G,范数||u++G表示(u~TGu)(?)。 相似文献
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本文的主要结果可概括为以下两部分:1.在文[1]基础上给出单调线性互补问题(MLCP)最小原则的形式和提出在有限步内可求出MLCP解集的两种方法;2.导出仅用MLCP的一个解的梯度和约束集即可刻划MLCP解集的充要条件. 相似文献
4.
等式约束加权线性最小二乘问题的解法 总被引:1,自引:0,他引:1
殷峭峰 《高等学校计算数学学报》1998,20(3):209-214
1 引言 在实际应用中常会提出解等式约束加权线性最小二乘问题 min||b-Ax||_M,(1.1) x∈C~n s.t.Bx=d, 其中B∈C~(p×n),A∈C~(q×n),d∈C~p,b∈C~q,M∈C~(q×q)为Hermite正定阵. 对于问题(1.1),目前已有多种解法,见文[1—3).本文将利用广义逆矩阵的知识,给出(1.1)的通解及迭代解法.本文中关于矩阵广义逆与投影算子(矩阵)的记号基本上与文[4]的相同.例如,A~+表示A的MP逆,P_L表示到子空间L上的正交投影算子,λ_(max)(MAY)表示矩阵M~(1/2)AY的最大特征值.我们还要用到广义BD逆的概念: 设A∈C~(n×n),L为C~n的子空间,则称A_(L)~(+)=P_L(AP_L+P_L⊥)~+为A关于L的广义BD逆. 相似文献
5.
线性流形上的逆特征值问题 总被引:6,自引:1,他引:5
戴华 《高等学校计算数学学报》1995,17(4):357-366
1 问题的提法先说明一些记号,R~(n×m)表示所有n×m实矩阵的全体。OR~(n×m)表示所有n×n正交矩阵的 相似文献
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一类线性互补问题的最小元算法 总被引:2,自引:0,他引:2
本文对M∈Z时的线性互补问题提出一种新的算法——最小元算法.此算法比现行的R.Chandrasekaran算法和化这类问题成线性规划问题的方法具有更广的适用范围,而且对于退化情形仍然有效. 相似文献
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程爱杰 《高校应用数学学报(A辑)》1994,(4):383-390
多孔介质中渗流驱动问题数值方法的研究,对合理经济地开发油田,了解地下油水运动规律有一定意义,特征线法结合差分或有限元法解渗流问题,在理论和应用上获得了成功,但还有很多问题进一步研究,前人研究多是假定流体不可压或微可压,本文研究一类完全可压缩两相驱动问题,采用特征线法与有限元法相结合,构造并分析了全离散数值格式,基于周期性假设,证明了最优L^2模误差估计。 相似文献
11.
Maria E. Schonbek 《Mathematische Annalen》2006,336(3):505-538
This paper considers the existence and large time behavior of solutions to the convection-diffusion equation u
t
−Δu+b(x)·∇(u|u|
q
−1)=f(x, t) in ℝ
n
×[0,∞), where f(x, t) is slowly decaying and q≥1+1/n (or in some particular cases q≥1). The initial condition u
0 is supposed to be in an appropriate L
p
space. Uniform and nonuniform decay of the solutions will be established depending on the data and the forcing term.This work is partially supported by an AMO Grant 相似文献
12.
A. Haraux 《NoDEA : Nonlinear Differential Equations and Applications》2006,13(4):435-445
We examine the rate of decay to 0, as t → +∞., of the projection on the range of A of the solutions of an equation of the form u′ + Au + |u|
p−1
u = 0 or u′′ + u′ + Au + |u|
p−1
u = 0 in a bounded domain of
N
, where A = −Δ with Neumann boundary conditions or A = −Δ − λ1
I with Dirichlet boundary conditions. In general this decay is much faster than the decay of the projection on the kernel;
it is often exponential, but apparently not always. 相似文献
13.
This paper deals with a coupled system of fourth-order parabolic inequalities |u|t ≥ 2u + |v|q,|v|t ≥ 2v + |u|p in S = Rn × R+ with p,q > 1,n ≥ 1.A FujitaLiouville type theorem is established that the inequality system does not admit nontrivial nonnegative global solutions on S whenever n4 ≤ max(ppq+11,pqq+11).Since the general maximum-comparison principle does not hold for the fourth-order problem,the authors use the test function method to get the global non-existence of nontrivial solutions. 相似文献
14.
Huashui Zhan 《Applications of Mathematics》2008,53(6):521-533
We study the large time asymptotic behavior of solutions of the doubly degenerate parabolic equation u
t
= div(u
m−1|Du|
p−2
Du) − u
q
with an initial condition u(x, 0) = u
0(x). Here the exponents m, p and q satisfy m + p ⩾ 3, p > 1 and q > m + p − 2.
The paper was supported by NSF of China (10571144), NSF for youth of Fujian province in China (2005J037) and NSF of Jimei
University in China. 相似文献
15.
In this paper, we consider the global existence, uniqueness and L
∞ estimates of weak solutions to quasilinear parabolic equation of m-Laplacian type u
t
− div(|∇u|
m−2∇u) = u|u|
β−1 ∫Ω |u|
α
dx in Ω × (0,∞) with zero Dirichlet boundary condition in tdΩ. Further, we obtain the L
∞ estimate of the solution u(t) and ∇u(t) for t > 0 with the initial data u
0 ∈ L
q
(Ω) (q > 1), and the case α + β < m − 1. 相似文献
16.
This work is concerned with the proof of Lp -Lq decay estimates for solutions of the Cauchy problem for utt -λ2(t)b2(t)/Δu =0. The coefficient consists of an increasing smooth function λ and an oscillating smooth and bounded function b which are uniformly separated from zero. The authors‘ main interest is devoted to the critical case where one has an interesting interplay between the growing and the oscillating part. 相似文献
17.
Flávio Dickstein Miguel Loayza 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2008,24(10):1-23
We consider the Cauchy problem for the weakly coupled parabolic system ∂
t
w
λ−Δ w
λ = F(w
λ) in R
N
, where λ > 0, w
λ = (u
λ, v
λ), F(w
λ) = (v
λ
p
, u
λ
q
) for some p, q ≥ 1, pq > 1, and
wl(0) = (lj1, l\fracq+1p+1j2)w_{\lambda}(0) = ({\lambda}{\varphi}_1, {\lambda}^{\frac{q+1}{p+1}}{\varphi}_2), for some nonnegative functions φ1, φ2
?\in
C
0(R
N
). If (p, q) is sub-critical or either φ1 or φ2 has slow decay at ∞, w
λ blows up for all λ > 0. Under these conditions, we study the blowup of w
λ for λ small. 相似文献
18.
Flávio Dickstein Miguel Loayza 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2008,59(1):1-23
We consider the Cauchy problem for the weakly coupled parabolic system ∂
t
w
λ−Δ w
λ = F(w
λ) in R
N
, where λ > 0, w
λ = (u
λ, v
λ), F(w
λ) = (v
λ
p
, u
λ
q
) for some p, q ≥ 1, pq > 1, and , for some nonnegative functions φ1, φ2
C
0(R
N
). If (p, q) is sub-critical or either φ1 or φ2 has slow decay at ∞, w
λ blows up for all λ > 0. Under these conditions, we study the blowup of w
λ for λ small.
相似文献
19.
We consider the nonlinear eigenvalue problem −Δu=λ f(u) in Ω u=0 on ∂Ω, where Ω is a ball or an annulus in RN (N ≥ 2) and λ > 0 is a parameter. It is known that if λ >> 1, then the corresponding positive solution uλ develops boundary layers under some conditions on f. We establish the asymptotic formulas for the slope of the boundary layers of uλ with the exact second term and the ‘optimal’ estimate of the third term. 相似文献
20.
The authors use the method of moving spheres to prove the nonexistence of ground states of -△u = u^p - u^q for n≥3,-∞〈p〈(n+2)/(n-2) and q〉max (1,p),
In fact this conclusion is a special case of -△u =f(u) for n≥2. 相似文献
In fact this conclusion is a special case of -△u =f(u) for n≥2. 相似文献