返回对象的函数保持不变。

Functions that return objects remain constant.

youdao

创建一个新的Array时将用到map函数，保持原始的数组内容不变，实际上大多数函数性程序员都喜欢这种方式。

The map function would be used where a new array was to be created, leaving the original array contents untouched, which is actually the way most functional programmers would prefer to operate.

youdao

在这一部分中，我讨论的是函数式编程的基石之一：不变性。

In this installment, I discuss one of the building blocks of functional programming: immutability.

youdao

They only depend on the state the system is in.

态函数是不变的，它们只依赖于。

麻省理工公开课 - 热力学与动力学课程节选

I'm using the fact that when you take a cosine and change the angle inside the cosine, it doesn't care. whereas, if you go to the sine and change the angle inside the sine, it becomes minus sine.

我用了一个结论,当你使用余弦函数时,改变角度的正负,函数值不变,而对于正弦函数,改变角度的符号,则函数值也会变号

耶鲁公开课 - 基础物理课程节选