{tex-core} is for questions that are independent of formats and macro packages. Such questions usually relate to low-level TeX programming or the behaviour of TeX at an underlying level. Note that even Plain TeX is a format in itself; for questions about it, use {plain-tex}.

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13
votes
1answer
714 views

How to change \hsize in the middle of a paragraph at pagebreak, especially for two-column?

The original question is: How to get two columns with different width in LaTeX? I know this older question: How can I create a two-column layout with different widths (and texts) for the two columns? ...
13
votes
1answer
589 views

Active characters let to a (non-active) character

It seems that if I \let\amp&, the alignment tab & can be replaced by \amp everywhere (e.g., in the preamble and in the body of an \halign). It is also possible to make the character & ...
12
votes
2answers
200 views

Define a shortcut (-> to \rightarrow) in plain TeX

I'ld like to make -> a shortcut for \rightarrow. Is that possible with Plain TeX or has it to do with the loaded font?
12
votes
2answers
136 views

What would be a suitable replacement for ifcsname in a non-etex situation?

From the pgfkeys.code.tex file: % This is useful: \def\pgfkeys@ifcsname#1\endcsname#2\else#3\fi{\expandafter\ifx\csname#1\endcsnam e\relax#3\else#2\fi}% \ifx\eTeXrevision\undefined% \else% ...
12
votes
4answers
968 views

Making efficient use of \writes

I'm currently trying to compile my thesis using LaTeX and have run up against the old ! No room for a new \write . problem. After some googling it seems the only way to actually resolve this problem ...
12
votes
2answers
555 views

The revenge of the vboxes

Yes, they're back. With a vengeance. Those pesky little buggers we call \vboxes which I've fought against previously. (And Bruno, too.) \parskip=0pt \def\unquo{\unvbox0\smallskip} ...
12
votes
3answers
575 views

Is there a printable version of a reference manual for all TeX primitives?

Everywhere in the TeX community, I see suggestions like \parskip, \obeylines, \parindent, etc. I'd be surprised not to find them even in the most basic LaTeX packages. So I figured they must be deeper ...
12
votes
3answers
315 views

Expansion of first token in a tabular cell

Background I currently do some work on the collcell package which collects the content of a tabular/array cell and provides it to a user defined macro, e.g. using ...
12
votes
3answers
502 views

Can I make a command not gobble spaces?

(I'm using ConTeXt, but I suspect the answer will lie in plain TeX.) I've created an environment that takes one argument myBufferName, and stores its contents in a buffer of that name. Unfortunately, ...
12
votes
2answers
243 views

All about \shipout

While reading about packages that allow to hook macros to certain events, I came across this command, \shipout. Searching on the internet didn't help a lot but if I'm not so wrong it's somehow related ...
12
votes
1answer
196 views

What does \empty do? [duplicate]

What does it do and what are its applications? I am currently testing the subtitle of my beamer presentation for its string length to decide about line spacings. Could it be simpler using \empty? If ...
12
votes
2answers
507 views

Why is \baselineskip not inserted before an \unvbox?

It seems that \setbox0=\vbox{\hbox{abc}}\unvbox0 is not equivalent to \hbox{abc}: the former does not insert a \baselineskip in the following situation. \vbox{% \hbox{XY}% \hbox{abc}% ...
12
votes
2answers
177 views

Can I detect whether a footnote has been split?

Title sez it all: Can I detect, hopefully by inspecting \box\footins, whether a footnote has been split at page-breaking? I found the package fnbreak but it uses labels, which is much too delayed for ...
12
votes
2answers
812 views

Globally redefining 1 pt to 1/72 in (PostScript point) and other similar changes

Introduction TeX point (1 pt in TeX) equals 1/72.27 in (= 2540/7227 mm ≈ 0.35145980351 mm). Quoting part of Traditional American point system section from Wikipedia's Point (typography) entry: In ...
12
votes
2answers
1k views

What does \relax do? [duplicate]

Possible Duplicate: How can I speed up LaTeX compilation? What is the difference between \relax and {}? The title suggest the question. On and off, I see macros here in TeX.SE and I see ...
12
votes
2answers
398 views

New lines and TeX: difference between ^^J and ^^M

What is a new line for TeX in the following contexts: When reading from a file. When writing to a file. After having read a % character. In a \scantokens. I am asking in particular because the ...
12
votes
1answer
252 views

\show with fewer lines?

I am writing some macros for general debugging purposes (See Yiannis' question). I am basically expanding a given input step by step, and printing the result to the terminal and log. In order for this ...
12
votes
1answer
66 views

Tight connection of \vbox es

I don't understand why TeX put a thin whitespace between my two vertical boxes: \documentclass{article} \begin{document} \vbox to 1cm {\rule{1cm}{1cm}} \vbox to 1cm {\rule{1cm}{1cm}} ...
12
votes
2answers
1k views

Write to log without wrapping

I'd like to to generate some metadata in the log file that I can copy to another application. But the log file is wrapped to 80 columns and I end up with newlines embedded in what I'm putting there. ...
12
votes
1answer
250 views

Test if a number is in a comma separated range/list of numbers

Martin Scharrer posted a very elegant answer for the question "Creating a zebra effect using listings". I want to extend that code to highlight only lines given in a comma separated list. The ...
12
votes
1answer
265 views

Is Knuth's *The TeXBook* complete?

Suppose I want to learn TeX. Then, is The TeXBook a complete source? Does it cover all relevant aspect of TeX? Or is there something worth learning about TeX which is not present there? Does also ...
11
votes
2answers
510 views

() or {} after a command

I was wondering why for some commands it is "(...)" that follows, while for other commands it is "{...}". For example, "\exp(x)" and "\bar{x}". Are both () and {} for specifying the arguments for the ...
11
votes
4answers
164 views

Partially expanding a command

My \john command is defined like so: \def\john{\DontExpandMe} I would now like to repeatedly change its definition, to keep adding some extra stuff on the front. \foreach\i in {ape,bat,cow,dog} { ...
11
votes
2answers
238 views

How does math mode work?

When writing an a in TeX, it is typeset as an upright "a" by default. When writing an a in math mode it is typeset in italics. Furthermore, in math mode white spaces are ignored and no empty lines ...
11
votes
2answers
1k views

Which “TeX” should one use?

This question is from my confusion with the editor. In the WinEdt 6.0, there is a button for different kinds of "TeX". How do I know which one I should use and what's the difference?
11
votes
3answers
266 views

Understanding etoolbox \ifdefempty and \ifdefvoid

I am trying to understand the etoolbox \ifdefempty and \ifdefvoid macros. The documentation says that \ifdefempty Expands to true if the control sequence is defined and is a parameterless macro ...
11
votes
2answers
140 views

Does a space belong after pt?

Does a space always belong after pt, e.g. as used in \hskip1pt? If a space is used, are there situations where a space will appear where it is not intended? If no space is used, will pt be ...
11
votes
2answers
184 views

Creating new primitives

Consider the following TeX: \tt ~~~[def]: \meaning\def \par ~~~[let]: \meaning\let \par [define]: \meaning\define \par ~[macro]: \meaning\macro \def\macro#1{some ...
11
votes
4answers
220 views

How can I compare two (not necessarily integer) variables?

After experimenting and researching for hours, I still cannot figure out how to perform a simple equality test between two numbers. More specifically, here, the two numbers in question are the ...
11
votes
2answers
938 views

Breakable vboxes

In Plain TeX how can I make vboxes breakable, and can I handle/measure them separately? What I'm trying to do, is that I have a portion of text, that is treated separately (no indention, narrower, ...
11
votes
1answer
727 views

What does the \the\everypar do?

If you test the following minimal it does not produce an error. What does it actually do? \the\everypar \bye Why doesn't it produce an error as one would expect?
11
votes
2answers
384 views

Is a TeX macro defined?

I am looking for a way in TeX to check if a macro was defined. Currently I use a rather tangled way. I exploit a sort of side effect when comparing two macros via \ifx; this command returns: true, ...
11
votes
4answers
102 views

A question about macro matching

Consider the following macro definition, and subsequent invocation: \def\foo #1 #2 \bar{stuff with #1 and #2 goes here} \foo arg1 arg2 \bar The \bar simply acts as the terminator for \foo. This all ...
11
votes
1answer
136 views

(Re)definition of commands that use delimiters other than braces (e.g. \underbrace)

How do you go about redefining a command such as \underbrace, which uses an "uncommon" delimiter, i.e. _, between its two arguments, so that the redefined command be usable in exactly the same way as ...
11
votes
2answers
453 views

\expandafter within a \begingroup … \endgroup [duplicate]

Possible Duplicate: What does \begingroup\expandafter…\endgroup do? In many of Heiko Oberdiek's packages one sees this type of construction: ...
11
votes
3answers
481 views

How to display only certain lines of a paragraph?

From reading Knuth's TeX Book (Chapter 14 How TeX Breaks Paragraphs into Lines), I understand that entire paragraphs are read in and then "massaged" by the "line-breaking algorithm" in an optimal way ...
11
votes
1answer
476 views

Consume/absorb a token

How does consume/absorb/remove a token from then token stream in TeX? I'm using @ifnextchar and would like to remove the character it matches.
11
votes
1answer
128 views

Begin/end a logical block?

Can I create a logical block (like HTML div element), so I can apply features like \centering locally, but not affect the outside environment?
11
votes
2answers
691 views

Tricks to make macros expandable

Expandable macros are useful (I find working in the lion's mouth super cool). But they are difficult to write. Can more experienced users give hints that help achieve expandability? For example, we ...
11
votes
1answer
371 views

Using \toks registers

I was reading this tutorial for TeX programming: http://pgfplots.sourceforge.net/TeX-programming-notes.pdf recommended in the 2-nd answer here: Where do I start LaTeX programming? It says: ...
11
votes
1answer
545 views

How to do \scantokens inside \edef without triggering “Runaway definition”

I'm trying to find a way to use the e-TeX \scantokens command inside [the equivalent of] an \edef (well, actually an \xdef, but presumably this does not make any real difference since that's just the ...
11
votes
1answer
134 views

What is the function of \noalign?

The use of \noalign is quite common. For example here \noalign is used with \vskip{}to control the height of a table cell. How does \noalign work in general, and how does it work with \vskip? ...
11
votes
1answer
170 views

Array functionality in TeX?

I've been using LaTeX for a while, but only recently I made myself a mission to create a class. I needed to learn the details of TeX, and I couldn't find answers to some of my questions. One of them ...
11
votes
1answer
819 views

Why does \hss fail?

Please why does the following fail? % \hss -> \hskip 0pt plus 1fil minus 1fil \setbox0=\hbox{a}% \setbox0\hbox to 10mm{\hss\unhbox0\hss} \unhbox0 And what makes LaTeX's ...
11
votes
1answer
647 views

From LaTeX with pdflatex to plain TeX

I've always wanted to try plain TeX instead of LaTeX. I can use plain but I'm not able to use correctly the fonts and I'm not able to use the french hyphenation. I would to know how to do this with ...
11
votes
1answer
550 views

How to prevent extra spaces between two specific words when justification occurs?

My document contains many short, justified lines, so the lines often appear with many spaces between words, e.g.: These words have a space so that they can fit nicely into the available ...
11
votes
1answer
122 views

XeTeXpicfile in vertical mode

Given a minimal like \line{% \vtop{\hsize=.6\hsize Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse tempor lectus sit amet laoreet convallis. Quisque at est lacinia, porttitor ...
11
votes
2answers
131 views

Document equivalence

What is the best way to determine, for two arbitrary input files, if they will result in the same compiled document (disregarding timestamp information and external files)? Context I'm attempting to ...
11
votes
2answers
365 views

Difference between unrestricted and internal vertical mode

At any point in the processing of a document, TeX can be in one of seven modes: no mode (only in \write and similar commands, I think), math mode ($...$), display math mode ($$...$$), restricted ...
11
votes
2answers
115 views

increase \hyphenation{word1 word-2…} capacity

We use LaTeX to typeset a large collection of books with many proper names. We use the \hyphenation{word1 word-2...} command to specify words that should not be hyphenated and to suggest hyphenation ...