共查询到20条相似文献，搜索用时 187 毫秒
1.
方欣华 《开封教育学院学报》1992,(4)
关于四元数正定(半正定、负定)自共轭矩阵的定义说:“设A是四元数体Q上的一个n阶自共轭矩阵,如果对Q上的任意非零行向量X=(x_1,x_2,…X_n)恒有XA(?)′>0(≤0或<0)(显然XA(?)′为实数)则说A是一个正定(或半正定、负定)的自共轭矩阵”。定义里包括了两个前提条件:①A是n阶四元数自共轭矩阵,②对于任意非零n维四元数组成的行向量X,恒有XA(?)′>0(≥0、<0)。 相似文献
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文章将对正定复矩阵的Schur补、k阶主子阵、Kronecker积和Hadamard积Sylvester阵的正定性进行讨论 ,给出一系列重要结论 ,证明了A ,B是正定复矩阵、半正定复矩阵 ,A与H(B)的kronecker乘积、A H(B)是正复矩阵、半正定复合矩阵这一重要结论。 相似文献
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讨论了矩阵方程X+A*X-nA=I在A为正定矩阵和酉矩阵时的正定解的存在性、唯一性、误差估计及存在正定解的必要条件,并且构造了数值求解的迭代方法. 相似文献
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研究了非线性矩阵方程X~s+A~*X~(-t)A=Q的Hermitian正定解的范围和存在条件,其中A为n阶非奇异复矩阵,Q为n阶Hermitian正定矩阵,参数s,t 0.基于矩阵几何理论、相关矩阵不等式和线性代数技术,针对参数s,t的不同取值范围,给出了Hermitian正定解的存在区间和方程可解的必要条件.比较已有的相关结果,所给出的Hermitian正定解的上界和下界估计更加精准,适用范围更广. 相似文献
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宋乾坤 《湖州师范学院学报》2003,25(6):9-11
给出了n阶复矩阵的广义Minkowski行列式的两个不等式：Idet(A B）1α≥2-sa/2（IdetAα IdetB1α)，其中A是n阶复半正定矩阵，B是n阶正定Hermite矩阵，a≥1/n，S是B^-1A的复特征值的个数；Idet(A B)I。≥(IdetAI。 IdetBI。)，其中A和B是n阶复半正定矩阵，且它们的特征值全为实数，r([A，B])≤1，a≥1/n，改进和推广了已有的结果。 相似文献
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何春羚 《河北理科教学研究》2007,(3):54-54
引理1 n阶实矩阵A对称正定的充分必要条件是存在n阶实对称正定矩阵B,使得A=B~2.引理2设A是n阶实正规矩阵,且它的特征值都具有正的实数部分,则A为正定矩阵.定理1设A,B∈R~(n×n),若A是对称正定矩阵,且(AB)(BA~(-1))~T=(AB)~T·(BA~(-1)),则AB是正定矩阵的充分必要条件是B的特征值的实部大于零,即Reλ(B)>0. 相似文献
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刘洪运 《商丘职业技术学院学报》2002,1(3):28-30
讨论Euclid空间中n阶实对称矩阵A是否正定,一直是矩阵理论中的重要问题。一改传统方法,从矩阵分解入手,逐步推导出一种新颖的判定方法,并给出将n阶实对称矩阵A分解为特殊三角矩阵与对角矩阵乘积的具体计算公式。 相似文献
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董会英 《唐山师范学院学报》1996,(Z1)
设A是n阶实阵,A有如下分解式 A=R(A) S(A)其中R(A)=(A A′)/2和S(A)=(A-A′)/2,分别称为A的对称分支和反对称分支。如果R(A)是正定阵,则称A是亚正定阵。 引理1 设A是n阶正定阵,则存在n阶正交阵Q,使得 相似文献
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杨树林 《中国石油大学胜利学院学报》2009,23(2):16-18
对非线性矩阵方程X+A*XqA=I,其中I是一个n×n阶单位矩阵,A是一个n×n阶复矩阵,推导出方程的解存在的充分条件和必要条件,得到了01两种情况下Hermite正定解的存在性以及迭代求解方法. 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献