integral of angular momentum

例句：

1. 1. The integral of a functionis the sum of its values at allpoints.
   一个函数的积分是其所有值的总和。
2. 2. The integral of a curveis the area under the curve.
   曲线的积分是曲线下方的面积。
3. 3. The integralof a function over a closed interval isequal to the definite integral of the function.
   函数在一个闭区间上的积分等于函数的定积分。