输入：phi是目标函数，a,b是搜索区间的两个端点 delta,epsilon分别是自变量和函数值的容许误差 输出：s,phis分别是近似极小点和极小值，G是n乘4矩阵- input: phi is the objective function, a, b is the search interval of two endpoints delta, epsilon, respectively is the independent variable and function