It's simply, notice the form of it here is, it's going to take two arguments, self self is the original instance.

这很简单，注意这里的格式，它有两个参数，你说对了，是原始的实例，and，you’re，right，也就是说。

麻省理工公开课 - 计算机科学及编程导论课程节选

French horn, yeah,but notice that if we take this aggregate-- and we're back to that same idea of the octave,the fifth,the fourth and the third, sort of,so it's again sort of primordial, this particular acoustical basis of so much of music.

法国号，对，但是注意，从总体的角度来看-,我们又回到了八度的概念，第五，第四，第三，大概是这样，所以这依然是是很基础的形式，许许多多音乐都是以这一种形式为声学基础的。

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take the derivative of this, get the velocity vector and you notice his magnitude is a constant Whichever way you do it, you can then rewrite this as v square over r.

对这个式子求一次导,就能得到速度矢量,你会发现其模长是常数,不管用什么方法,加速度也可以写成 v^2 / r

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