So, we said when we have a function of two variables, we have the gradient vector.

我们说，当一个二元函数存在时，就有梯度向量。

youdao

we've seen is how to actually view a function of two variables in terms of its graph and its contour plot.

我们学过怎样认识二元函数,从它的图像和等高线的角度来看。

youdao

I should say that is for a function of two variables to try to decide whether a given critical point is a minimum, a maximum or a saddle point.

但这种办法并不普遍，只能用于二元函数，来判断是极小值点、极大值点还是鞍点。

youdao

I should say that is for a function of two variables to try to decide whether a given critical point is a minimum, a maximum or a saddle point.

但这种办法并不普遍，只能用于二元函数，来判断是极小值点、极大值点还是鞍点。

youdao