无约束问题最优化方法的核心问题是选择搜索方向。

以正定二次函数为例，来观察两个方向关于矩阵Ａ共轭的几何意义-Unconstrained optimization problems are most core issue is to choose the search direction. In definite quadratic function, for example, to observe both directions on the matrix A conjugate geometric meaning