具有与多项式复合齐次相容的项序

设K[x1,X2,…,xn]是域K上关于变量x1,x2,…,xn的多项式环,θ=(θ1,…,θn)是K[x1,x2,…,xn]的一组有序多项式.多项式复合θ是用θi代替xi的一种运算.我们说多项式复合θ与项序>齐次相容,是指对任意项P与q,p>q,deg p=deg q(→)polt(θ)>qolt(θ).怎样判断多项式复合与项序>是否齐次相容是困难的.将给出明确的判定方法.     

关于实系数代数多项式根的分布

给定一实系数多项式:p(z)=a_0z~n a_1z~(n-1) … a_n,不失一般性,假定a_0>0.本文主要给出有关多项式(1)的根的分布的结果.定理1 如果系数{a_i}_i=0~m满足条件△~2a_k≥0,k=0,1,2,…,(n-1),其中△~2 a_k是二级差分,那么多项式(1)的所有根位于圆|z|<1外.     

Z/pkZ上的多元置换多项式

设Z表整数集,p为一给定奇素数,k为一正整数.张起帆(1995)得到了一类模p奇异的二元多项式成为剩余类环Z/pkZ上的置换多项式的一个充要条件,胡永忠(2001)将张起帆的这一结果的充分条件推广到了一般n元的情形.本文得到了一类模p奇异的n元多项式成为剩余类环Z/pkZ上的置换多项式的一个充要条件,所得结论是对张文(n=2)和胡文(n＞2)的自然推广和改进.     

实二次多项式正定性的判定

讨论n元实二次多项式f(x1,x2,…,xn)=(1 xT)A1x(x=(x1,…,xn)T)正定性的判定方法.     

关于多项式系数的整除性

设 n是正整数 ,k1 ,k2 ,… ,ks 是适合 k1 +k2 +… +ks=n的非负整数 ,正整数 nk1 k2 … ks=n!k1 !k2 !… ks!称为多项式系数 .本文讨论了当n=a0 +a1 p+a2 p2 +… +arpr ,其中 p为素数且 p≤ n,0≤ ai相似文献   

关于多项式系数的整除性

设n是正整数,k1,k2,…+k1=n的非负整数,正整数[nk1k2…ks]=n！/k1!k2!…k5!称为多项式系数,本文讨论了当n=a0+a1p+a2p^2+…arp^r,其中p为素数且p≤n,0≤ai&;lt;p(0≤i≤r);ki=a0^(i)+a1^(i)p+…+ar^(i)p^r,其中ki≤0,∑^si=1,ki=n,0≤ak^(i)p(0≤i&;lt;s)时多项式系数的整除性问题,得出的结果推广了著名的Lucas定理^[1].     

多项式零点的存在区域

考虑n次多项式p(z)=α_nz~n+a_(n-1)z~(n-1)+…+a_1z+a_0,其中a_i,i=0,…,n,是复数,a_oa_n≠0. 本文研究了p(z)的零点所存在的区域.利用多项式友阵的概念证明了一些新的圆环区域,这些区域的界限都可通过p(z)的系数算出.这里的结论优于许多已知的结果.     

多项式方程组的主项解耦消元法

本文提出多项式组符号求解的主项解耦 (主项只含主元 )消元法 :视多项式为变元不同幂积的线性组合 ,以主项解耦三角型多项式组 DTS为引导 ,用逐项伪除求余式 ,将多项式组 PS化为与其同解的 DTS.内容涉及 :消元算法、DTS的存在性与结构特性、零点集结构公式等 .亦对 Grobner基法、吴文俊消元法与本文方法之间的相互联系、区别以及特点进行了比较 .研究表明主项解耦消元法适用于一般多项式组且效率较高     

一个联系Fisher信息和Amari曲率的极限定理

其中 x=(x_1,x_n)~T 是一随机向量,θ=(θ~1,…,θ~n)~T 是未知参数.θ∈H,H 是 R~n的一个开凸集.本文将采用 Einscein 求和约定.在以上条件下由(1.1)式确定的分布密度的集合形成一个 n 维的微分流形 S.我们考虑一个光滑地嵌入在 S 中的(m,n)-曲指数族 M,其元素可表示为 p(x,θ(u)),其中u=(u~1,u~m)~T,m相似文献   

用Dickson多项式构造差集

最近,Dillon和Dobbertin证明了在有限域Fq(q=2m)的乘法群中,多项式(x+1)d+xd+1(其中d=22k-2k+1)的像集是一个新的具有Singer参数的循环差集.利用有限域上的Fourier分析,本文证明了在有限域Fq(q=2m)的乘法群中,一些用Dickson多项式构造的集合是具有Singer参数的循环差集.     

A penalty method for the time-dependent Stokes problem with the slip boundary condition and its finite element approximation

We consider the finite element method for the time-dependent Stokes problem with the slip boundary condition in a smooth domain. To avoid a variational crime of numerical computation, a penalty method is introduced, which also facilitates the numerical implementation. For the continuous problem, the convergence of the penalty method is investigated. Then we study the fully discretized finite element approximations for the penalty method with the P1/P1-stabilization or P1b/P1 element. For the discretization of the penalty term, we propose reduced and non-reduced integration schemes, and obtain an error estimate for velocity and pressure. The theoretical results are verified by numerical experiments.     

Newton's method and a surface with Jacobian zero

Suppose a system of nonlinear real equations P(x)=0, where P and x are n-dimensional vectors, is solved by means of the continuous analog of Newton's method. We study the behavior of the method near the surface S with Jacobian zero: S={x¦det P′(x)=0}. A computational strategy is suggested in the case where the method diverges.     

A $\mathbb{P}_N × \mathbb{P}_N$ Spectral Element Projection Method for the Unsteady Incompressible Navier-Stokes Equations

In this paper, we present a $\mathbb{P}_N × \mathbb{P}_N$ spectral element method and a detailed comparison with existing methods for the unsteady incompressible Navier-Stokes equations. The main purpose of this work consists of: (i) detailed comparison and discussion of some recent developments of the temporal discretizations in the frame of spectral element approaches in space; (ii) construction of a stable $\mathbb{P}_N × \mathbb{P}_N$ method together with a $\mathbb{P}_N → \mathbb{P}_{N-2}$post-filtering. The link of different methods will be clarified. The key feature of our method lies in that only one grid is needed for both velocity and pressure variables, which differs from most well-known solvers for the Navier-Stokes equations. Although not yet proven by rigorous theoretical analysis, the stability and accuracy of this one-grid spectral method are demonstrated by a series of numerical experiments.     

Symbolic Computation of Lax Pairs of Partial Difference Equations using Consistency Around the Cube

A three-step method due to Nijhoff and Bobenko & Suris to derive a Lax pair for scalar partial difference equations (PΔEs) is reviewed. The method assumes that the PΔEs are defined on a quadrilateral, and consistent around the cube. Next, the method is extended to systems of PΔEs where one has to carefully account for equations defined on edges of the quadrilateral. Lax pairs are presented for scalar integrable PΔEs classified by Adler, Bobenko, and Suris and systems of PΔEs including the integrable two-component potential Korteweg–de Vries lattice system, as well as nonlinear Schrödinger and Boussinesq-type lattice systems. Previously unknown Lax pairs are presented for PΔEs recently derived by Hietarinta (J. Phys. A, Math. Theor. 44:165204, 2011). The method is algorithmic and is being implemented in Mathematica.     

ORDER PROPERTIES AND CONSTRUCTION OF SYMPLECTIC RUNGE-KUTTA METHODS

1. IntroductionFOr a given s stage Runge-Kutta methodwith A = [ail], p = [pl, PZt... 5 P.]T and ac = [afl, ry23... ) %]T / 0, we introduce thefollowing simplifying conditions as in Butcher [1]and make the notational convensionwhere 1 5 m? pi(x), i ~ 1, 2, 3,' ? are arbitrarily given i--th polynomials with the property that pi(0) = 0,Note that B(P), C(P) and D(P) are equivalent to BI,. = 0, CI,P = 0 and DI,. = 0respectively. We shall always denote BI,., CI,., DI,. and VI,. by B, …     

关于P4P问题解数的一些研究

本文研究了计算机视觉中P4P问题的多解问题,运用几何方法,分析了P4P问题的多解现象,获得了P4P问题存在5个解的必要条件.     

精确分布推导的一个基本的方法

寻求统计量的精确分布,在数理统计的理论中是一个重要的问题。然而,在多元统计分析中,往往很不容易得到统计量的精确分布,有些统计量的分布,例如非中心的Wishanrt分布,持续了几十年,还没有获得完满的结果。我国的许宝騄先生早在1939年,就得到了正态总体样本协差阵的特征根的联合分布(参看[1])。据徐钟济先生的回忆,当时R.A.     

透视3点问题临界构造算法及实现

P3P问题是计算机视觉和摄影测量学领域的一个经典问题.运用基于求解非线性代数方程系统的吴特征列elimination方法,在计算机符号计算系统Maple 9上实现了透视3点问题临界构造解的求解,编制了一个小型实用的程序.运用Maple 9实现的模拟试验结果说明了我们的算法是稳定的.     

Trigonometrically fitted predictor–corrector methods for IVPs with oscillating solutions

In this paper we develop a trigonometrically fitted predictor–corrector (P–C) scheme, which is based on the well-known two-step second-order Adams–Bashforth method (as predictor) and on the third-order Adams–Moulton method (as corrector). Numerical experiments show that the new trigonometrically fitted P–C method is substantially more efficient than widely used methods for the numerical solution of initial-value problems (IVPs) with oscillating solutions.     

污染物排放总量分配的群体决策方法研究

污染物排放总量控制是防治污染的重要途径,污染物排放权的分配是区域污染物排放总量控制工作的核心.本文提出了经济最优性(P1方案)、合理公平性(P2方案)和经济发展连续性(P3方案)的污染物排放权分配原则,研究了以P1方案、P2方案和P3方案为基点的群体决策方法,给出了污染物总量分配的群体决策分配模型.