解决了最小无约束优化问题　 步长由ARmijo非精确一维搜索生成，迭代方向分别由最速下降法，阻尼牛顿法，共轭梯度法，拟牛顿法(BFGS)产生(This code solves the minimum unconstrained optimization problem, and the step size is generated by ARmijo inexact one-dimensional search. The iterative directions are generated by steepest descent method, damped Newton method, conjugate gradient method, and quasi Newton method (BFGS) respectively)