用最速下降法求二元函数f(x)=2*x1^2+x2^2,的最优解，初值设为【1,1】，误差限设为0.1,并且给出了函数的等高线图，给出了点的轨迹-Find the steepest descent method with the binary function f (x) = 2* x1 ^ 2+ x2 ^ 2, the optimal solution, 1,1】 【initial set, the error limit is set to 0.1, and gives the function contour map, the path to there is some