{macros} is for questions specifically concerning TeX's macro processor. Note that, because TeX uses macros ubiquitously, most questions about code that uses macros are not looking for information about how macros work, and so are not appropriate for this tag.

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19
votes
3answers
2k views

How do magic \dots work in amsmath?

The amsmath package redefines the \dots command so that it "guesses" the correct height of the dots with respect to its context. For example $x, \dots, y$ will produce three lowered dots, aligned ...
19
votes
1answer
555 views

Why \( and \) were not defined as robust commands in the first place?

I am aware of the difference between using \(...\) and $...$ (in moving arguments, for example), and yes, I've read the answers to this question: Are \( and \) preferable to $?). I also know the ...
18
votes
9answers
2k views

fibonacci numbers

Hi I am trying to do Fibonacci below is the code but I am getting some error \newcount\n \newcount\np \newcount\npp \newcount\m \newcount\f \def\fibonacci#1{{\ifnum #1<3 1\else \np=1\npp=1\m=3 ...
18
votes
11answers
783 views

Storing an array of strings in a command

I want to store three strings in a variable \mydata like the following: \storedata\mydata{one}{two}{three} Then I want to extract the first/second/third string in the following way: ...
18
votes
5answers
340 views

How retrieve items in a list of words by number?

I'm working on a character sheet for the Fate RPG, which rates its skills with a numerical scale that corresponds to an adjective scale. I've been trying to write a macro that will take \skillAdj{4} ...
18
votes
4answers
857 views

How to define a command that bolds the first letter of each word in the input argument?

I want to define a command that takes a sentence, a word or several words as input and bolds the first letter of each word. I need this mostly for abbreviations and so far I have done it manually in ...
18
votes
5answers
6k views

new command with cases / conditionals / 'if… then's

Suppose I want to define a command, say, \tree with, say, two arguments. I would like \tree to do different things depending on what my first argument is. For example, if #1 = a, then return ...
18
votes
3answers
502 views

What is the difference between local and global in a TeX meaning?

In tikz declare function and babel french option it came to the question about the difference between local and global in a TeX meaning. In the liked question the babel shorthand ; should be ...
18
votes
3answers
1k views

Doing an interlinear text

I want to produce a three-line interlinear text with numbers and asterisks in the top line, Greek in the middle, and the vernacular (Portugese) in the bottom. An example is below: The challenge, as ...
18
votes
4answers
688 views

How exactly does \def\p@figure{Figure~} work?

I took this line from my thesis style and added it into my document (preceded by \makeatletter) and what it does that whenever I used \ref{figureid} instead of putting just the figure number, it puts ...
18
votes
3answers
2k views

Why does LaTeX make a distinction between commands and environments?

Why does LaTeX make a distinction between commands and environments? Or also: why do we need environments? I ask this because I am defining a number of custom commands (like \question{} and ...
18
votes
2answers
633 views

How to display command name and its value

Latex displays the command values by default - I am finding it more difficult to display the command names along with the values. I have a list of commands that I would like to loop over and print ...
18
votes
2answers
1k views

Difference between \let\foo\relax and \def\foo{} for disabling

When I want some macro to (temporarily) do nothing, I normally write \let\foo\relax But somebody asked me why I don't just do \def\foo{} and I realized I couldn't answer his question. So, I ...
18
votes
2answers
278 views

How can I improve my “hands-on”/ “working” knowledge of TeX's low/middle/high/higher -level control sequences?

I am not an experienced TeX/LaTeX user. I know just about enough to write my thesis. As my interest grows, I'd like to continue improving on my TeX/LaTeX knowledge, more specifically, my "working" ...
18
votes
2answers
415 views

How can I redefine my macro to accept a charcode instead of a character?

I recently posted this answer to How to highlight all words of the form [0-9][A-Za-z0-9]* immediately following an equal sign?. It works, but it suffers from (a lot) of code duplication. What I have ...
18
votes
1answer
831 views

Abbreviations and full stop--how to avoid double dots?

I have trouble with macros expanding to an abbreviated expression. Say I have \WHP which expands to "with high prob." (artificial example). I want to avoid the dot after the abbreviation colliding ...
18
votes
1answer
734 views

What does \p@ mean in some code?

I have found the source code within octavo.dtx (from the octavo package) and it has some parts called \p@. I have searched throughout the document, but cannot understand what this is defined as or ...
18
votes
1answer
882 views

What does the # symbol do in LaTeX?

I know most of the effects of the special characters in LaTeX, like \ is used for most commands, or $ is used for opening or closing the math ambience, but I don't know what the symbol # does, and I ...
18
votes
1answer
821 views

babel shorthand "| doesn't work in macros

The package babel with the ngerman option (and most other languages as well, but not english) provides the shorthand "|, which prevents a ligature at the given position (see p. 81 of the babel ...
18
votes
2answers
9k views

When should you use \vskip (\hskip) rather than \vspace (\hspace) in a LaTeX document?

I assume that, to guard against strange errors, you should use \vspace rather than \vskip whenever possible in a LaTeX document. But are there any situations in which you must use \vskip? I'm ...
18
votes
2answers
8k views

Block comments with *% and %*

I know the package comment which allows to use : \begin{comment} Lines to comment \end{comment} This is not very friendly to use. I would like to have the following possibility: *% Lines to ...
17
votes
4answers
922 views

On/Off switch (redefine a macro at each use)

I try do define a macro \onoff, which alternatively prints "on" and "off" each time it's used. For example the sequence \onoff \onoff \onoff would print on off on My first guess would be to use the ...
17
votes
3answers
870 views

Conditionally Remove Brackets

I'm trying to create a command with an optional argument using \newcommand{\Af}[1]{{\mathbf{A}_{(#1)}} where the argument is a number. However, I'd like that if no argument is given the bracket ...
17
votes
3answers
1k views

What is the purpose of hash (#) as a special character sign?

I understand the purpose of all special characters, $, &, %, _, {, }, ^, ~, and \, but just except for hash (#). When and why should it be used?
17
votes
4answers
2k views

No space present after ensuremath

When I insert a short maths section in a sentence, it renders fine with a space each side as expected: ...returned $\mathcal{P}$ from... If I define a command to do the same thing, it also renders ...
17
votes
3answers
816 views

What does \\* do?

I have some code, and when I use \\*, it causes some things to become unaligned, but when I use \\, the alignment is correct. What's the difference?
17
votes
3answers
2k views

Conditionals in \newcommand

I find myself using the \newcommand macro a lot and apart from having the occasional difficulty with properly defining the optional parameter the macro works well. There is one serious limitation ...
17
votes
3answers
554 views

What is the exact purpose of \ftype@<TYPE>?

I currently working on some float related code an saw that the standard float environments figure and table define (beside others) the macros \def\ftype@figure{1} and \def\ftype@table{2}. The LaTeX ...
17
votes
3answers
2k views

Doing maths with distance values in LaTeX source code

I have a sty file with the command \newcommand{\foo}[1]{\noindent\kern#1} but I'd actually like to have something like \newcommand{\foo}[1]{\noindent\kern{#1 *0.5}} meaning that I'd like to have ...
17
votes
3answers
417 views

newcommand does not work with \fi

I tried the command \newcommand{\fistudenti}{\fi} but it seems to work properly only in some cases. Here below there are two insances when it works and when it does not: WORKS: ...
17
votes
5answers
998 views

How to apply a macro to each column of a table

I want to apply a macro to all the cells of a column with the cell content as the input to the macro. Is this possible? For example if the cell contents have the word TEST, the macro should take TEST ...
17
votes
4answers
613 views

Extract the numerical and non-numerical portion from text

I would like to extract the leading number and subsequent text from a string. I have an idea of using the xstring package to gobble characters from the right until I end up with a number or an empty ...
17
votes
4answers
348 views

Is it possible to add an “or” condition to a \def?

Is it possible to have something like \def\fiveorsix{5,6 OR 6,5} So that the following works: \documentclass{standalone} \def\fiveorsix{5,6 OR 6,5} \makeatletter \newcommand{\test}[1][]{ ...
17
votes
2answers
322 views

Why do some commands use []s, some use {}s, and some use both?

I find it confusing to remember which commands take {} arguments, and which ones take [] arguments. Is there a rule-of-thumb or semantic difference between these two? If so, what? (Because they seem ...
17
votes
2answers
387 views

Why does this simple \ifx test fail?

This should be easy, but I don't understand why the test below fails... I expected Hurrah! to be printed when the \currentchar count reaches 90 (i.e. the character code of Z). There must be some ...
17
votes
4answers
8k views

\span as a math operator

I'd like \span to be a math operator (for the span of a set of vectors), but apparently it's already a TeX command. What do you guys recommend I do instead? (I don't really want a strange capital ...
17
votes
3answers
2k views

Defining commands that are scoped to a particular environment

Is it possible to define commands in a separate namespace so that they only work within a particular environment? For example, can I create a package named foo that defines a foo environment and a ...
17
votes
2answers
294 views

Why is unskip not working here?

I'm trying to define a macro to be used as follows: \usepackage[normalem]{ulem} \newcommand{\thesis}[1]{\uline{\ignorespaces #1\unskip}} % underlining required by school - I know, I know % later... ...
17
votes
1answer
495 views

Newcommand: What cannot be done?

It is not the first time I tried to create a new command unsuccessfully. Some things I found out did not work (getting "undefined control sequence" or other errors). Use a quote-endquote argument. ...
17
votes
5answers
6k views

\vec{x} but with arrow from right to left?

I have two variables: \vec{x} and another one which is somehow dual to the first. Therefore I would like to symbolize the second with something similar but a leftarrow on top of the x. I already tried ...
17
votes
1answer
345 views

Why doesn't \makeatletter work inside \newcommand?

After hours of banging my brain against my skull, I narrowed down an issue I'm having to the fact that \makeatletter doesn't work inside \newcommand. Commands that I call after \makeatletter are ...
17
votes
2answers
264 views

Can I turn a collection of optional parameters into a macro?

I currently have several environments from mdframed that have a large number of options that are shared between them. The situation looks like \newmdtheoremenv[options0,options1]{env1}{Environment 1} ...
17
votes
2answers
661 views

Selecting random elements from a comma separated list

I would like to have a command (either user-defined, or from a package, or whatever) that has the basic form: \selectNrandom{N}{list, of, comma, separated, elements}{code to execute} which will ...
17
votes
2answers
744 views

Macros in LaTeX and in programming languages

There is a fairly widespread consensus that macros are a bad idea in most programming languages. (For example, cf. http://scienceblogs.com/goodmath/2007/12/17/macros-why-theyre-evil/ .) That said, I ...
17
votes
1answer
586 views

How do I make a macro require math mode?

I have defined a macro that I would like to be used exclusively in math mode. In order to enforce this, I would like the macro to throw an error message whenever it is used outside of math mode. What ...
17
votes
1answer
4k views

Comparing an argument to a string when argument is a result of a command with etoolbox

I've got an example like that: \documentclass{article} \usepackage{etoolbox} \newcommand{\ab}{a} \newcommand{\aORb}[1]{% \ifstrequal{#1}{a}{"a" was given}{not a}, % ...
17
votes
2answers
2k views

Difference between \relax and % for ending a line

when would I use one over the other? Are they the same?
17
votes
1answer
2k views

Define same command with different amount of parameters

I want to define two versions of the command \Set, depending if I provide one or two parameters. I.e. like this: \newcommand{\Set}[1]{\bigl\{ #1 \bigr\}} \newcommand{\Set}[2]{\bigl\{ #1 \bigm| #2 ...
17
votes
1answer
1k views

biblatex: Is it possible to patch macros created with \newbibmacro?

This question led to a new feature in a package: xpatch The etoolbox package provides various tools that "are useful to hook into or modify existing code" (etoolbox manual, section 3.4). The ...
17
votes
5answers
3k views

Proper way to detect empty/blank text

I am attempting to ignore a command if it is passed with empty/blank text. My use case is not as complicated as one Expand away empty macros within ifthenelse where @egreg provides what seems like a ...