对基于稀疏矩阵存储技术的对称正定稀疏矩阵进行LDL分解，C++编写-LDL is a set of concise routines for factorizing symmetric positive-definite sparse matrices, with some applicability to symmetric indefinite matrices. Its primary purpose is to illustrate much of the basic theory of

实对称正定矩阵LDL^分解，其中L为单位下三角矩阵，D为对角阵-A recursive algorithm for calculating the eigenvalues of a real symmetric matrix based on LDLT decomposition is given. With this algorithm, the number of eigenvalues of a real symmetric matrix in the given interval c