{expl3} is the programming "language" written for the LaTeX3 project. It is a library of common functions for storing and manipulating data and performing higher-level logical tasks than commonly provided for in TeX and LaTeX.

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Latest MiKTeX-Update broke XeLaTeX with fontspec

I updated MiKTeX a few days ago and since then I cannot compile XeLaTeX with fontspec anymore. \documentclass{article} \usepackage{fontspec} \begin{document} Hello world! \end{document} When I try ...
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LaTeX3: Defining key to set boolean variable

I want to define a key, which, if set, sets a boolean variable to false. The documentation is not clear on that point. It states (source3.pdf, sect. 87, p. 134): Defines <key> to set ...
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LaTeX3: expansion of argument to function

I would like to define functions which extract the PDF object number from a PDF object reference, such as 12 from 12 0 R. I defined two versions of such a function, a low level one and a high level ...
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What's the deal with Tex Live and expl3.sty?

I've installed Tex Live 2010 on a mac, and when trying to use xelatex, I get the error: !Latex Error: File `expl3.sty' not found What is this package, and how can I get it installed on tex live? ...
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How can I define NaN in LaTeX3

LaTeX3 l3fp offers a way to check if a variable has a an infinite value. The following code defines a number and then sets its value to π/2. It then calculates tan(π/2) to get a large result. ...
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How do I use the sin function in LaTeX3

I am exploring some of the LaTeX3 routines and syntax. How do I get to use functions such as sin etc. I get an error with the sin function in the following (please uncomment sin function to view the ...
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What LaTeX Lab packages use expl3?

I am trying to migrate documents to http://latexlab.org, but they won't compile because they require expl3.sty. Yesterday I started by uploading all of the expl3 sty files but then latex demanded even ...
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How can I make RHEL server libraries compatible with tex/Rnw documents created on my Ubuntu desktop, re: pgf, tikz, expl3

I want to compile tex and Sweave documents written on a server that is redhat, but I get errors linked to pgf/tikz. The documents compile fine on my I have already used wget to download the expl3 ...
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What are expl3 quarks? When, where, why and how should I use them?

I feel particularly bombarded by sub-atomic particles right now (and it's mostly Will's fault :)). First, in Will's answer to this question today, he referred to expl3's \prg_case_str:nnn command. ...
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A LaTeX3 macro to typeset chemical compounds?

Out of curiosity I wonder how would a macro coded in expl3 that does the basics of mhchem (as in section basics in mhchem manual) looks like? I have found examples in TeX and LuaTeX in ...
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Pros and cons of the LaTeX3 syntax?

The programming language introduced by expl3 in LaTeX3 is a bit unusual compared to other TeX macro languages in that it uses both _ and : for function names. Could someone provide some technical ...
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Will LaTeX3 have proper support for hooks? Does LuaTeX?

Tex has powerful support for extensions triggered by events happen in generating output, by running one of six token lists appropriately: \everycr \everydisplay \everyhbox \everymath \everypar ...