1. 梯度是导数对多元函数的推广，它是多元函数对各个自变量偏导数形成的向量，其作用相当于一元函数的导数。函数![](https://cdn.nlark.com/yuque/__latex/393cb29364d46207d27905f0fea6b44e.svg#card=math&code=f%28x_1%2C%5Cdots%2Cx_n%29&id=qYgt3)的梯度是对所有自变量的偏导数形成的向量。<br />![](https://cdn.nlark.com/yuque/__latex/a534eee8ed88fb249ca5c85e007a743c.svg#card=math&code=%5CDelta%20f%28x%29%3D%28%5Cfrac%7B%5Cpartial%20f%7D%7B%5Cpartial%20x_1%7D%20%5Cdots%20%5Cfrac%7B%5Cpartial%20f%7D%7B%5Cpartial%20x_n%7D%29%5ET&id=pMAHg)