本文给出了上(下)三角形矩阵的一个求逆公式。
This article gives a Formula for finding inverse matrices of upper (down) triangular matrix.
给出了一类上三角形矩阵可交换的充要条件，并由此得到了求其逆矩阵的一种简便方法。
The exchangeable necessary and sufficient condition is given for a class upper triangular matrixes, and out of it, we have got a simple method of obtaining inverse matrixes.
选定平面三角形基函数作为型函数，确定了单元方程和单元矩阵；
The triangle base function was selected as shape function, and cell equation and cell matrix were constructed.
推导了轴对称线性三角形元的影响系数矩阵和输入向量公式；
The influence coefficient matrix of the linear axisymmetric triangular element and the input vector expression are derived.
应用亚参元的概念将这些矩阵推广应用于任意三角形单元。
Then these matrice are transformed to arbitrary triangular element by the concept of subparameter.
本文在已有的索单元力密度矩阵的基础上推导了三角形膜单元的力密度矩阵。
On the basis of force density matrix of cable element, a force density matrix of triangle membrane element is introduced.
本文首次定义和推导了移位切比雪夫多项式(第一类和第二类)的分离矩阵，它具有简洁的递推关系和三角形结构。
The separative matrices of shifted Chebyshev polynomials of the first and second kinds, which have a nice structure and an elegant recursive formula, are introduced at the first time.
应用高精度的六节点三角形单元进行单元划分，建立复合夹层板的刚度矩阵、质量矩阵并推导有限元动力学方程。
Elements by the highly-accuracy six-node triangular element are divided. Stiffness matrix and mass matrix of sandwich panel are established and then deduced dynamical equations of finite elements.
应用高精度的六节点三角形单元进行单元划分，建立复合夹层板的刚度矩阵、质量矩阵并推导有限元动力学方程。
Elements by the highly-accuracy six-node triangular element are divided. Stiffness matrix and mass matrix of sandwich panel are established and then deduced dynamical equations of finite elements.
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