正定矩阵

This thesis has mainly contributed two results in theory: one is that the covariance matrix is not positive definitive if the number of sampling is least than the number of variables, the other is that the covariance matrix of discrete sample is positive definitive if and only if the sum of every random column vector of data matrix is non I-linear combination.

本论文在理论上，主要得出两个新的结果：ⅰ抽样调查中，若样本的个数少于变量的个数则样本协方差矩阵恒为非正定；ⅱ离散型样本协方差矩阵正定的充要条件是样本资料阵的各随机列向量是非I-线性组合。

In a special case of 2 dimensional variables, the probability of the positive definitiveness of the discrete sample covariance matrix is given in term of sample size and variable dimension. Based on the results, the optimal sample size is provided in this thesis.

推出了离散型样本协方差矩阵正定的充要条件，得到了求离散型样本协方差矩阵正定概率的模型，建立了特殊情况下的抽样优化模型。

The algorithm consists of a least-squares part providing an analytica l initial solution,and a projection part that projects the initial least-square s solution successively onto each equality constraint.

该算法有两个显著特点：一是目标函数的Hessian矩阵不要求正定；二是由于采用平方根因子分解来计算增广Hessian矩阵及投影算子矩阵，算法具有很好的数字稳定性。

By using the matrix positive definite decomposition, matrix singular value decomposition generalized inverse theorem, and solving the linear matrix inequality, an explicit expression of the desired observer is derived in the light of some free parameters.

通过利用矩阵正定分解，矩阵的奇异值分解，解线性矩阵不等式和广义逆定理，根据一些自由参数所希望设计的观测器然后被导出。

Missirlis in article [1]. At the same time, a sufficient condition for convergence of the PSD method is given to be compared when the coefficient matrix A of the linear system Ax = b is a symmetric, positively defective matrix. In §3.2, an example is given to state that the range of our sufficient condition is wider than theorem 3.3 of article [1]. On the other hand, following a.n analogous approach of [14] and starting the functional relationshipwe have a perfect analysis for the PSD method to converge and optimum valves for the involved parameters under different conditions.Under the assumptions that A is a consistent ordered matrix with nonvanishing diagonal elements and the eigenvalues of the Jacobi matrix of A are real,we get necessary and sufficient conditions for the PSD method to convergence.The result is equal to theorem 1 of article [9].Under the same condition, we can see the optimal parameter and of corresponding spectral radius of thePSD method in [8]:(2)When A is a consistent ordered matrix with nonvanishing diagonal elements and the eigenvalues of the Jacobi matrix of A are imaginary or zero,we get necessary and sufficient conditions for the PSD method to convergence.In chapter 3, the optimal parameter and of corresponding spectral radius of the PSD method are given by table 3.3. Moreover, under the assumption 0

Missirlis在文献[1]中定理3.3的不准确，同时给出了当线性方程组Ax=b的系数矩阵A为对称正定阵时，PSD迭代法收敛的一个充分条件与之比较，并且在§2.3中用实例说明了对于一部分矩阵而言本文得到的充分条件广于[1]中定理3.3的充分条件；另一方面，按照文献[14]的方法，我们从PSD迭代法的特征值λ与其Jacobi迭代矩阵B的特征值μ的关系式：出发，在不同条件下对PSD迭代法的收敛性和最优参数以及最优谱半径进行了完整的分析：(1)在系数矩阵A为(1，1)相容次序矩阵且对角元全不为零，其Jacobi迭代矩阵B的特征值全为实数的条件下，给出了PSD迭代法收敛的充分必要条件，此结果与[9]中的定理1等价，此时最优参数及最优谱半径由[8]得：(2)第三章表3.3中给出了，当系数矩阵A为(1，1)相容次序矩阵且对角元全不为零，其Jacobi迭代矩阵B的特征值全为纯虚数或零时的PSD迭代法的收敛范围和最优参数，并且我们可以得到当0

At last the consistently symmetrical and positive definite properties between the energy matrices and the elastic matrices are clarified by using the theory of positive definite quadratic form of matrices.

最后，运用矩阵的正定二次型理论阐述了"能量矩阵与弹性矩阵"之间一致的对称性和正定性。

Under the assumption that a differential Riccati equation is solvable, an exponential reduced-order observer is developed by means of coordinate transformation and the gain matrix of the proposed observer depends on the solution of the differential equation.

在一微分Riccati方程有正定解的前提下，通过坐标变换方法对该类系统提出了一种指数型降维观测器设计方法，该观测器的增益矩阵取决于微分Riccati方程的正定解。

This paper sets forth non zero element dynamic memory trigonometric decomposition method of large scale sparse positive definite normal equation, which is regular, simple and intuitive, and therefore it is ease to realize in the computer.

本文针对具有正定性质的大型稀疏法方程，提出了大型稀疏正定法方程的非零动态存储三角分解法，运用复式链表来动态存储稀疏矩阵。

Necessary and sufficient conditions for the matrix equation to have symmetric positive semidefinite solutions are derived using the generalized singularvalue decomposition.

利用广义奇异值分解导出了该矩阵方程有对称半正定解的充分必要条件，并且给出了一般对称半正定解的表达式

In the last of this dissertation, we give necessary and sufficient conditions for the existence of and the expressions of perpositive semidefinite solutions and bipositive semidefinite solutions to some systems of quaternion matrix equations.

给出了某些四元数矩阵方程组有广亚半正定解，双半正定解的充要条件及其表达公式；研究了矩阵方程组的最小二乘解，极小范数的最小二乘解，在某些约束条件下的最小二乘解和极小范数的最小二乘解，给出了其有这些解的充要条件及其表达公式。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷