symmetric arrow-head matrices

Secondly we consider two kinds of the least-squares problems for inverse problems of symmetric arrow-head matrices,discuss the conditions under which they have solutions,and derive the expressions of the least-squares solutions. The corresponding algorithms are presented to compute the least-squares solutions.
3.关于问题Ⅲ,研究了一类对称箭形矩阵逆问题有唯一解的充分必要条件,给出了求解的算法;研究了二类对称箭形矩阵逆问题的最小二乘解,讨论了问题有解的条件,并给出了解的表达式,给出了相应的两个计算最小二乘解的算法。