为什么变量"i"和"j"表示用于柜台? [英] Why are variables "i" and "j" used for counters?
问题描述
我知道这似乎是一个绝对愚蠢的问题，但是我很好奇，不想问...
I know this might seem like an absolutely silly question to ask, yet I am too curious not to ask...
为什么"i"和"j"成为在大多数控制结构中用作计数器的变量?
尽管常识告诉我它们就像X一样，用于表示未知值，但我不禁要认为一定有一个原因，使得每个人都一遍又一遍地以相同的方式进行教学.
Although common sense tells me they are just like X, which is used for representing unknown values, I can't help to think that there must be a reason why everyone gets taught the same way over and over again.
是因为实际上建议将其用于最佳实践或惯例，还是背后隐晦的原因?
Is it because it is actually recommended for best practices, or a convention, or does it have some obscure reason behind it?
以防万一，我知道我可以给他们我想要的任何名称，并且变量名称无关.
推荐答案
它最终来自数学:求和表示法传统上将 i 用于第一个索引，将 j 用于第二个，依此类推.示例(来自 http://en.wikipedia.org/wiki/Summation ):
It comes ultimately from mathematics: the summation notation traditionally uses i for the first index, j for the second, and so on. Example (from http://en.wikipedia.org/wiki/Summation):
它也用这种方式来收集事物，例如，如果您有一堆变量x 1 ，x 2 ，... x n ，那么任意一个将称为x i .
It's also used that way for collections of things, like if you have a bunch of variables x1, x2, ... xn, then an arbitrary one will be known as xi.
关于为什么会这样，我认为SLaks是正确的，这是因为我是Index中的第一个字母.
As for why it's that way, I imagine SLaks is correct and it's because I is the first letter in Index.
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