Maths — your first formula
LaTeX Lesson 5 1:59 English narration · English + 中文 subtitles burned in
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Transcript
This is what LaTeX is famous for.
这就是 LaTeX 出名的原因。
Put dollar signs around something and everything between them is set as MATHS.
在某段东西两边加上美元符号，它们之间的一切就会按"数学"来排版。
Look at what changes: the letters lean, the spacing around the equals sign opens up, and the two lifts into a power.
看看什么变了：字母变斜了，等号周围的间距张开了， 而那个 2 升上去变成了幂。
Maths mode is a different typesetter, with its own rules about all of that.
数学模式是另一个排版器，关于这一切它有自己的规则。
Two keys do most of the work.
两个键干了大部分活。
A caret raises what follows into a power.
尖号把后面的东西抬上去变成幂。
An underscore lowers it into an index.
下划线把它压下去变成下标。
And you can use as many as you like in one formula — x squared plus y squared equals r squared is three carets in one line, and LaTeX sizes and places every one of them.
而在一个公式里你想用多少个都行—— x² + y² = r² 一行里就有三个尖号， 而它们的大小和位置全都由 LaTeX 安排。
Here is the trap.
这里有个坑。
A caret takes exactly one thing.
尖号只接受恰好一样东西。
Write x caret one zero and only the one goes up — the zero stays on the line, and you get something that looks nearly right and is wrong.
写 x^10，只有那个 1 会上去——0 留在了基线上， 于是你得到一个看起来几乎对、其实是错的东西。
For more than one character, group them with braces.
多于一个字符时，用花括号把它们括起来。
That is what braces are for throughout LaTeX: they turn several characters into one thing.
这就是花括号在整个 LaTeX 里的用途： 它们把好几个字符变成"一样东西"。
For an important equation you do not want it squeezed into a line of prose.
对于一个重要的公式，你不会希望它被挤在一行散文里。
Use backslash square bracket instead of dollars and it becomes DISPLAY maths: its own line, centred, set larger, with space above and below.
用 \ 代替美元符号，它就变成了"独立公式"： 自己占一行、居中、字号更大、上下都留出空白。
Same formula, different presentation — and the choice says how important it is.
同一个公式，不同的呈现方式—— 而这个选择本身就说明了它有多重要。
Four things to take with you.
带走四点。
One: dollars put maths inside a sentence.
第一：美元符号把公式放进句子里。
Two: square brackets put it on its own centred line.
第二：\ 把它放到独立的一行、居中。
Three: a caret raises a power and an underscore lowers an index.
第三：尖号抬起幂，下划线压下下标。
Four: more than one character needs braces around it.
第四：多于一个字符时要给它加花括号。
Now write your formula and press Run.
现在把你的公式写出来，然后按 Run。