你在 TeX Stack Exchange 看到過哪些令人驚嘆的回答？

01-12

聯動問題：你在 MathOverflow 上看到過哪些令人驚嘆的回答？ - 數學

我看得比較少，立馬能想起來的有這麼幾個

macros - How to implement (low-level) arrays in TeX，TeX 的哈希碰撞和 fontdimen 的另類用法。
best practices - Detecting unused packages in LaTeX document，實現很暴力。
xetex - The ^^ notation in various engines，這個回答最後部分顯示 XeTeX 字元串那部分。這個在新版的 XeTeX 中已經被修復了。
boxes - Measure a very large vbox，怎麼測量一個高度大於 maxdimen 的盒子。
spacing - Mathematical description of TeX"s infinite numbers?
counters - How to suppress page 13? active 被挪用成數字 13 了。
In LuaTex is it possible to change font/language according to the script/glyphs used? XeTeXinterchartoks 的 LuaTeX 模擬。正如在評論中提到的，LuaTeX 的這個模擬，功能上要比 XeTeX 的弱很多。

其實要說「令人驚嘆」的回答的話，腦子裡瞬間浮現出的回答有三個。

第一個是劉海洋前輩那個「如何找到一個宏在哪個宏包中定義」的回答，第二個是有人用 TikZ 繪製了一個心臟的解剖圖，第三個是一個有趣的問題「如何給奶奶講解 LaTeX」。

tex core - How to find out where a macro is defined?

tikz pgf - Can we make a love heart with LaTeX?

How can I explain the meaning of LaTeX to my grandma?

當然，其實這個心臟解剖圖，是從矢量圖裡導出的 TikZ 代碼，並不是答主真的一點一點去繪製的。

如果要說有益的回答，那見過的就太多了。除掉中文處理方面（中文處理方面的精華大都在 CTeX 論壇），TeX.SX 上的幾個大牛的高票回答都很不錯。以下是一些精選。

TeX 相關文檔推薦

http://tex.stackexchange.com/questions/24105/what-are-good-advanced-latex-books/24131#24131

Any Known comprehensive tutorial about TeX fonts

TeX 核心以及相關概念

tex core - What is the basic mechanism for writing something to an aux file?

http://tex.stackexchange.com/questions/20304/is-there-a-show-for-catcodes/20305#20305

http://tex.stackexchange.com/questions/27631/how-latex-compiler-is-written/27632#27632

tex core - What"s new in TeX, version 3.14159265?

tex general - Why is % the comment character?

tex core - What is truecm?

Is XeTeX a complete rewrite of LaTeX/TeX?

tex core - How does TeX actually work?

宏編寫

macros - What do newcommand, renewcommand, and providecommand do, and how do they differ?

macros - Where are the necessary places to be appended with % to remove unwanted spaces?

macros - What is the difference between let and edef?

macros - What is the difference between ifxsomecommandundefined and ifdefinedsomecommandelse?

macros - What are the differences between
ewdimen,
ewskip and
ewlength?

macros -
ewcommand vs DeclareRobustCommand

key value - A package template using xkeyval?

macros - What exactly do csname and endcsname do?

macros - When to use LetLtxMacro?

macros - Understanding @ifnextchar

macros - What does ifx\#1\ stand for?

tex core - Difference between if and ifx

tex core - letfooar vs letfoo=ar

macros - What is the difference between vskip and vspace?

macros - How to know whether or not we need expandafter?

tex core - On the basics of writing to reading from auxiliary files (.aux, .toc, etc.)

tex core - Advantages and disadvantages of fully expandable macros

boxes - setbox vs. sbox and savebox

tex core - Is it really bad to use makeatletter and makeatother in a package or class file?

tex core - What is the differences between mathcode and catcode and how can I use mathcode?

繪圖

3d - Draw an aircraft with Tikz

http://tex.stackexchange.com/questions/60778/fundamental-differences-pstricks-tikz-pgf-and-others/60797#60797

圖表

http://tex.stackexchange.com/questions/45498/choosing-whether-to-include-pdf-or-png-in-pdflatex/45502#45502

數學公式

best practices

math mode - What is the Necessity of $...$ Around Numbers?

amsmath - Is there a preference of when to use ext and mathrm?

math mode - Defining `$$$ $$$` to align（這個有點黑科技）

fractions - What is the difference between over and frac?

math mode - Why is [ ... ] preferable to $$ ... $$?

http://tex.stackexchange.com/questions/104004/xy2-or-xy2/104005#104005

macros - What』s behind over?

其他細節

spacing - Lengths and when to use them

margins - Difference between extwidth, linewidth and hsize

Absolutely, definitely, preventing page break

compiling - What"s the maximum number of pages a PDF produced by pdfTeX can have?

line breaking

counters - How to suppress page 13?

嗯，其實我也有一段時間沒看 TeX.SX 了，而且翻大牛們以前的答案也只是詳細翻了劉海洋前輩， egreg 和 David 的。所以這個列表肯定還差得遠啦。另外，從列表裡也可以看到我關注的 topics，其實也不一定適合知乎上的朋友們，所以最好還是自己去尋找啦。

TeX.SX 上有益的討論很多，大家如果想看，可以按照這樣的方式去找。

Users - TeX - LaTeX Stack Exchange 這裡列出了 TeX.SX 上的活躍用戶
尋找你比較喜歡的作者
戳進去（以 David 為例）：User David Carlisle
在 Answers 里點 View more：User David Carlisle
愉快地看起來~

我比較喜歡的幾位答主：

http://tex.stackexchange.com/users/2674/leo-liu
User David Carlisle
http://tex.stackexchange.com/users/4427/egreg
User Heiko Oberdiek
User Joseph Wright
User Herbert
User Stefan Kottwitz
User Martin Scharrer

現在去得比較少了。看了一下我的收藏夾，相對而言實用的東西多些，或者一些零碎的小技巧什麼的，讓人驚嘆的東西就比較少。

說到驚嘆，大概有兩種，一種回答是有奪目效果的炫技之作，配個明顯一般很難用 TeX 做出來的排版效果圖，然後貼一長段代碼或扔個鏈接出來；另一種是詳實厚重壓得人喘不了氣的回答。

前一類的代表，比如 Showcase of beautiful typography done in TeX friends 中由 ?aphink 給出的排名第一的回答，用 XeTeX 排版的 16 世紀法語聖經。是這個樣子：

後一類則以 LaTeX3 小組領導 Frank Mittlebach 的部分回答為代表。比如 How to influence the position of float environments like figure and table in LaTeX? 這個問題的回答，介紹 LaTeX 的浮動體機制，篇幅很長，瀏覽器需要滾動好幾屏才能看完，比許多專門的書籍總結得還要詳細。當然，對這類問題的回答，更常見的方式是給出詳細文檔的鏈接，而不是直接在 TeX.sx 上發一篇可以在 TUGboat 上發表的帖子。就舉這麼兩個例子。