{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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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?
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4answers
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\aftergroup a list of tokens

\aftergroup executes the next token after the end of the current group. Is there a variant, \Vaftergroup{\some\tokens\a\b} that would put \some\tokens\a\b after the current group ends? Of course, one ...
15
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4answers
911 views

File copy without expansion

What is the command for file copy? I want to copy the contents of one file into another without any command expansion. In a command line driven operating system one would use copy source target I ...
15
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3answers
386 views

Parsing strings containing diacritical marks (macros?)

I apologize that this question may seem very much like several other recent ones I have asked (Parsing leading hardspaces, Parsing a \$ as part of an improved \getargs command). They are all related ...
15
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2answers
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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, ...
15
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2answers
373 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?
15
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3answers
1k views

TeX macro and command expansion?

I have implemented couple of macros that should remove commas from numbers. It's nasty dirty stuff, but it works when input is number: \removecommas{12,34,56.7} % => 123456.7 But it stop working ...
15
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1answer
595 views

What is the programming term for the command invoking '\' in latex?

I don't think it would be called a delimiter. Is there a specific term for this character? Just to clarify, I'm talking the slash here: \frac{1}{2}
15
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2answers
264 views

\expandafter with \uppercase ordering

As I understand it, the behavior of \expandafter is such that if \a and \b are macros, then \expandafter\a\b will first expand \b then \a. But my understanding must be wrong, because I don't ...
15
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2answers
756 views

What is “plain TeX”?

I occasionally see a statement that plain TeX is not the same as TeX, because plain TeX is already a format. What is plain TeX, and what is the difference to TeX proper? Some answers are here (The ...
15
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4answers
358 views

Using the filename in the document?

I have a bunch of documents called wk01.tex wk02.tex and so on up to (eventually) 20. These are weekly handouts for a course I TA. Currently, each document starts with a \def\classweek{5} or whatever. ...
15
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2answers
499 views

Why does `x_\text y` work?

As far as I have understand the tokenization in LaTeX, x_\text y will be split up into x _ \text y Now the _ will consume/bind to the next token. However, \text takes an argument as well. If _ ...
15
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3answers
247 views

How to determine which register a count uses

Suppose there is \newcount\c@mycountera \newcount\c@mycounterb \newcount\c@mycounterc Each \newcount uses \alloc@ and that has \wlog{\string#5=\string#2\the\allocationnumber}. Thus to determine ...
15
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2answers
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How to add a hook to a macro

LaTeX uses hooks extensively, one method employed is the command g@addto@macro. It is defined in source2e as: \long\def\g@addto@macro#1#2{% \begingroup \toks@\expandafter{#1#2}% ...
15
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3answers
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\def taking rest of the line as argument

I know how to define a macro that will take the rest of the paragraph as parameter. Simply write \def\a#1\par{\textbf{#1}}. But, how do I write a macro whose argument will extend to the end of the ...
15
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1answer
522 views

productivity tools

I am using latex to write a mathematically dense document which has several hundred differential forms and products. There must be better ways than just typing out the whole equations line by line. ...
15
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1answer
308 views

\def two macros with same name, but different argument syntax

Is it possible to have macros with the same name, but different “syntax”? E.g. we have the primitive \font which could be seen as having 3 arguments(a. without size information; b. giving the ...
15
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2answers
223 views

Test whether \end will really end the run

Can I test whether calling the \end primitive will really end the run? The naive \ifdim\pagegoal=16383.99998pt yes\else no\fi is not sufficient (even adding to that mix \deadcycles). According to ...
15
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3answers
683 views

Unbalanced output routine

The TeX primitive \output behaves almost like a toks register, except in the fact that it is always surrounded by braces. For instance, after \output={\plainoutput}, the result of \showthe\output is ...
15
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1answer
499 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 aspects of TeX? Or is there something worth learning about TeX which is not present there? Does "TeX ...
15
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1answer
485 views

Interwoven alignment preambles are not allowed - what exactly does this mean?

I admit that this post is purely idle curiosity. But I recently stumbled upon a little factoid saying that the TeX error "Interwoven alignment preambles are not allowed" has the following explanation ...
15
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1answer
458 views

How can latex and pdflatex be both symbolic links to same executable (pdftex) and not behave the same?

When I run $ latex my_doc.tex and $ pdflatex my_doc.tex it works, and when I run $ pdftex my_doc.tex it doesn't work. The thing is I noticed that both LaTeX and pdflatex commands are ...
15
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1answer
505 views

How do I ‘expand’ a control sequence `\let` to a character?

Consider the following: \let\1=X \edef\2{\1} \show\1 \show\2 The result is > \1=the letter X. > \2=macro: ->\1. Is it possible to ‘expand’ the meaning of \1 so that \2 contains just ...
15
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1answer
270 views

How to read a stream of tokens up to one of two different delimiters

The core question How can I process text delimited by one of two terminators? For instance, if I want to process text up to the next \A, I can just write \def\CmdA#1\A{...} But suppose that \A ...
15
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1answer
2k views

How to transpose a table in expl3

I've been very impressed with xparse and expl3, and have written a wonderful document command using \ProcessList that takes a comma separated list and turns it into a (basically) 1 column table. ...
15
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1answer
237 views

Am I programmatically tieing my hands behind my back by insisting on a particular engine?

I've read Differences between LuaTeX, ConTeXt and XeTeX, but still have a niggle at the back of my mind that I'd like to ask about. I'm developing a LaTeX package/class/stuff with the aim of making ...
14
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3answers
799 views

How could the macro xii.tex be simplified into a better readable form

I was reading some TeX guides from where I have found this source: \let~\catcode~`76~`A13~`F1~`j00~`P2jdefA71F~`7113jdefPALLF PA''FwPA;;FPAZZFLaLPA//71F71iPAHHFLPAzzFenPASSFthP;A$$FevP ...
14
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4answers
1k 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 ...
14
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2answers
698 views

Why using character ^^ff before every chapter in the TeXBook source

When viewing the source code of the TeXBook, I find that there is a character ^^ff before every chapter in it. I am wondering why using this ^^ff character which seems useless? The following ...
14
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3answers
742 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 ...
14
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2answers
273 views

How can own commands be aware of \global?

When I define a command that defines commands \def\makefoobar{ \def\foo{foo} \def\bar{bar} } and prefix it with \global { \global\makefoobar } it is treated like { \global\def\foo{foo} ...
14
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2answers
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Why (La)TeX can not work with true type fonts?

I know that if one wants to use true type fonts, there are solutions via xelatex or lualatex. My question however is, why it is like so? What is the fundamental difference between latex fonts and ...
14
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2answers
1k 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, ...
14
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2answers
181 views

Can I get at stuff in “current page” or “recent contributions”?

When I compile the following, \documentclass[a4paper]{article} \usepackage{atbegshi} \AtBeginShipout{\showlists} \showboxdepth\maxdimen \showboxbreadth\maxdimen \usepackage{lipsum} ...
14
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3answers
287 views

What other macros like \pdffilesize exist?

So I just learned about \pdffilesize from this answer. Are there other similar things like this? I learned about \the\inputlineno a while ago which prints the line number of the input file. In ...
14
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2answers
956 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 ...
14
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2answers
412 views

How to set tikzmarks with \noalign at the edge of tabular rows

I'm trying to improve the lines in a tabular with colored rows (lines above a colored row can disappear in the adobe reader at some zoom levels) by redrawing the line above a row after the row itself ...
14
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3answers
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How can I open a file in “append” mode?

Could not find anything in the TeXBook, but this could be just me. I guess it is always possible to open the file for reading, copy its content to another file, and then continue writing to that ...
14
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2answers
400 views

Every possible \meaning that a token can have

In the context of a debugging package that I am writing, I need to analyse an arbitrary token in the input stream. What are the possible outcomes of \meaning<token>? Macro: (\protected) ...
14
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1answer
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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: ...
14
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2answers
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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 ...
14
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1answer
1k views

What is the command \span?

I have bumped into the \span primitive a couple of time. I got the impression it is defined in the TeX program, not even in plain.tex. Is that right? And what does that command do and what is it for?
14
votes
1answer
2k 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 ...
14
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3answers
3k views

How to use \valign?

I just bumped into a interesting command called \valign. It seems to be the sister of \halign, but the TeXbook seems to be rather shy on explaining its use. As is the TeX by Topic. They only mention ...
14
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1answer
249 views

How to actually close a write-stream

I don't know too much about writing and reading to and from files. But I managed to create a nice command for me where I need to write something into a text-file and later-on read it again. ...
14
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2answers
257 views

Use TeX macros to store multiple data

I'm trying to use TeX macros to store multiple data such as website url/name. Here is an example : \documentclass{article} \def\Google{{http://www.google.com}{Google Search}} \makeatletter ...
14
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2answers
158 views

Unicode math at TeX primitive level

I am looking for information how to implement Math OTF font in XeTeX or LuaTeX at TeX primitive level (using XeTeX or LuaTeX primitives). There exist a LaTeX package unicode-math. Unfortunatelly, this ...
14
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1answer
383 views

How to write a two-pass system in TeX?

On page 400 of The TeXbook ("Dirty tricks" part) it is said: An output routine can also write notes on a file, based on what occurs in a manuscript. A two-pass system can be devised where TeX ...
14
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2answers
246 views

What is the easiest way to modify catcodes in a string?

Assume that a token register contains a sequence of letter tokens, each having a catcode of 12. I want to store in a second token register the same sequence of letter token, altering some catcodes on ...
14
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1answer
301 views

What practices are there regarding the use or avoidance of “internal” TeX or LaTeX commands?

What practices are there regarding the use or avoidance of "internal" TeX or LaTeX commands? (About "command" vs "macro", there is some discussion in this TeX.SX answer, though I don't know whether ...