主对角线

A determinant in which all elements are zero except the elements of the principal diagonal and the elements immediately above and below this diagonal is called a continuant.

一个行列式除了主对角元素以及紧靠对角线的上面和下面的元素外，所有的元素均为零者叫做连行列式。

A general mathematic model of lifting subsystem and hydraulic balancing subsystem was set up by using correspond relation of the force and the displacement at the interface of lifting and hydraulic system, then the question that the principal diagonal elements of mass matrix were zero is resolved. Meanwhile the effect on the general dynamic characteristic of ellipticity of is considered.

通过卷扬系统与液压系统在界面耦合处的力和位移协调关系，建立诸如M〓+C〓+KX=F形式的机械卷扬-液压均衡系统综合数学模型，模型中考虑了卷筒椭圆度偏差以及直径偏差对整体动态性能的影响，解决了耦合后数学模型质量矩阵主对角线元素奇异的问题。

The characteristic vector of the real symmetric matrix should be found out, which is orthogonalized and normalized to a standard orthogonal base and is used as row vector to construct the transformation matrix P, so the P~(-1)AP can be made into diagonal matrix.

实对称矩阵A经相似变换P-1AP可化为对角矩阵，在x =Py 下，不一定能化A的二次型为标准型；应寻求对称矩阵A的特征向量，将其正交化并单位化作为标准正交基，作为列向量构造变换矩阵P，可使P-1AP=Λ为对角阵，在x =Py 下，要将二次型化为标准型，且二次项系数即为对角阵Λ主对角线上元素。

Since all elements on the primary diagonal are 1' s and the dimensions are less than 2006, the graph with A 2006 as its adjacency matrix is the transitive closure of the graph represented by A .

由于主对角线上的元素都是1，而且矩阵的阶小于2006，所以为 A 2006邻接矩阵的图就是由 A 表示的图的传递闭包。

On the basis of the advantages of the previous distillation calculation algorithms, by eliminating the non—zero elements to the two sides of the tridiagonal band of elements in the component material balance equations by correlation of the draw rate from the main column to the sidestrippers and the return vapor stream from the sidestrippers to the main column, it changes these equations into a typical form of the tridiagonal matrix, and uses the simultaneous convergent strategy of the main column and the side strippers to speed the algorithm convergent rate.

在吸收前人蒸馏计算算法优点的基础上，通过求解主塔抽出到汽提塔的量和汽提塔返回主塔的蒸汽流之间的关联，以便消除组分物料平衡方程组系数阵中的三对角线两边的非零元素，使它转化为典型的三对角矩阵形式，而且使用主塔和汽提塔同时收敛策略，加快了算法收敛速度。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐