用显式最速下降法求正定二次函数的极值

function [x,minf]=minDefTW(f,A,x0,var,eps)

目标函数：f

正定矩阵：A

初始点：x0

自变量向量：var

精度：eps

目标函数取最小值时的自变量值：x

目标函数的最小值：minf-　Explicit steepest descent method the positive quadratic function of the extreme value function [x, minf] = minDefTW (f, A, x0, var, eps)　target function: f　positive definite matrix: A　Initial Point: x0　argument vector: var　Accuracy: eps　minimum value of an objective function value of the argument: x　minimum target function: minf