You use this downward pointing triangle as the notation for the gradient.

用▽表示,这就是梯度的符号。

youdao

To model inheritance on a class diagram, a solid line is drawn from the child class (the class inheriting the behavior) with a closed, unfilled arrowhead (or triangle) pointing to the super class.

为了在一个类图上建模继承，从子类(要继承行为的类)拉出一条闭合的，单键头(或三角形)的实线指向超类。

youdao

To model inheritance on a class diagram, a solid line is drawn from the child class (the class inheriting the behavior) with a closed, unfilled arrowhead (or triangle) pointing to the super class.

为了在一个类图上建模继承，从子类(要继承行为的类)拉出一条闭合的，单键头(或三角形)的实线指向超类。

youdao