The arrow is the gradient vector at the point.[br][br][math]f\left(x_1,x_2\right)=\frac{1}{100}\left(x_1^2+x_2^2\right)\left(\left(x_1-5\right)^2+\left(x_2-1\right)^2\right)\left(\left(x_1-2\right)^2+\left(x_2-3\right)^2\right)[/math]