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Getting Started with PreTeXt: COMaT Workshop, May 2024

Steven Clontz, Oscar Levin

Chapter 2 Write Once, Read Anywhere

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Section 2.1 Setting up Codespaces

A Codespace is an authoring environment that lives in the “cloud”, that is, a virtual machine hosted by GitHub that has all of the software needed to create great accessible documents, accessible with just a web browser.
This coding environment uses a web version of Virtual Studio Code, an open-source editor, along with the PreTeXt community’s custom plugins and software to get started authoring quickly.
Follow the instructions at https://github.com/PreTeXtBook/pretext-codespace to get started. Let this run for a few minutes in the background while you review the rest of this section.

Note 2.1.1.

Codespaces works best in the Chrome or Edge web browsers.

Section 2.2 PreTeXt Principles

A more detailed monograph on PreTeXt’s philosophy
 1 
pretextbook.org/doc/guide/html/philosophy.html
is availabe in the PreTeXt Guide.
List 2.2.1. PreTeXt Principles
  1. PreTeXt is a markup language that captures the structure of textbooks and research papers.
  2. PreTeXt is human-readable and human-writable.
  3. PreTeXt documents serve as a single source which can be easily converted to multiple other formats, current and future.
  4. PreTeXt respects the good design practices which have been developed over the past centuries.
  5. PreTeXt makes it easy for authors to implement features which are both common and reasonable.
  6. PreTeXt supports online documents which make use of the full capabilities of the Web.
  7. PreTeXt output is styled by selecting from a list of available templates, relieving the author of the burden involved in micromanaging the output format.
  8. PreTeXt is free: the software is available at no cost, with an open license. The use of PreTeXt does not impose any constraints on documents prepared with the system.
  9. PreTeXt is not a closed system: documents can be converted to and then developed using standard tools.
  10. PreTeXt recognizes that scholarly documents involve the interaction of authors, publishers, scholars, curators, instructors, students, and readers, with each group having its own needs and goals.
  11. PreTeXt recognizes the inherent value in producing material that is accessible to everyone.

Section 2.3 PreTeXt is XML

Since PreTeXt uses the XML markup language, all content is structured in terms of elements. The root pretext element nests many other elements inside of it. This is accomplished by surrounding everything with a starting <pretext> tag and an ending </pretext> tag. (Folks with HTML experience will find this pattern familiar, akin to the “HTML” root element.)
Listing 2.3.1 is a very simple PreTeXt/XML document. (The first line is boilerplate that lets various programs know the rest of the file is XML, and the third-to-last line is an example of a comment that won’t appear in the output.)
<?xml version="1.0" encoding="UTF-8"?>
<pretext>
    <article>
        <title>Hello world!</title>
        <p>Welcome to PreTeXt!</p>
        <!-- TODO: find something more to say... -->
    </article>
</pretext>
Listing 2.3.1. Source of a simple PreTeXt book project.

Section 2.4 Books and Divisions

There are several documents you can write in PreTeXt, such as <article>s and <slideshow>s. This tutorial will focus on <book>s.
A <book> typically includes <frontmatter>, and <backmatter>.
Between <frontmatter>, and <backmatter> are either several <chapter>s or <part>s. If used, <part>s are subdivided into <chapter>s. Then <chapter>s subdivide into <section>s, and <section>s can have <subsection>s.
Each of these subdivisions needs a <title>, and may have an <introduction> or <conclusion>.
Listing 2.4.1 puts some of these elements together for a simple PreTeXt project (information on the other elements will come in later sections).
<?xml version="1.0" encoding="UTF-8"?>
<pretext xml:lang="en-US">
  <!-- (author configurations go in docinfo) -->
  <docinfo>
    <macros>
      \newcommand{\R}{\mathbb R}
    </macros>
  </docinfo>


  <book xml:id="my-great-book">
    <title>My Great Book</title>
    <subtitle>An example to get you started</subtitle>

    <frontmatter xml:id="frontmatter">
      <titlepage>
        <author>
          <personname>You</personname>
          <department>Your department</department>
          <institution>Your institution</institution>
        </author>
        <date>
          <today />
        </date>
      </titlepage>
    </frontmatter>

    <chapter xml:id="chapter-welcome">
      <title>Welcome!</title>
      <introduction>
        <p>This chapter is about the real numbers <m>\R</m></p>
      </introduction>

      <section xml:id="section-getting-started">
        <title>Let's get started</title>
        <p>Can you solve <m>ax^2+bx+c=0</m>?</p>
      </section>

      <section xml:id="section-learning-more">
        <title>But wait, there's more!</title>
        <p>Did you know that <me>x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}</me>?</p>
      </section>

    </chapter>

    <backmatter xml:id="backmatter">
      <title>Backmatter</title>

      <colophon>
        <p> This book was authored in <pretext />. </p>
      </colophon>

    </backmatter>

  </book>

</pretext>
Listing 2.4.1. Source of a simple PreTeXt book project.

Section 2.5 Paragraphs, Lists, and Blocks

Within each division (chapter, section, etc., see Section 2.4) of your book, you likely want some content (e.g. what you’re reading right now!).
Written content is usually structured as paragraphs, <p> for short. If you’ve ever written HTML, this tag may be familiar to you, but be warned: while PreTeXt is XML (Section 2.3), PreTeXt is not HTML! There is some overlap: you can emphasize words or phrases with <em> for instance. However, while HTML uses the full word “code” for its tag, PreTeXt uses the shortened <c> tag.
Note that these elements are all semantic: they express the meaning of content, not its presentation. For example, the word “semantic” was a <term>, we just defined, while we merely emphasized “meaning” with <em>. The presentation of these concepts may vary by output format, likely using some combination of boldface, italics, or underlining.

Heads up!

We’ll talk about customizing presentation later, but it’s important to remember that the PreTeXt community separates such “publication” decisions away from the work of “authoring” content.
For users coming from LaTeX, rest assured your mathematical formulas work in PreTeXt. Inline mathmode \(ax^2+bx+c=0\) is invoked with <m>ax^2+bx+c=0</m>, while display mathematics like
\begin{equation*} x=\frac{-b\pm\sqrt{b^2-4ac}}{2a} \end{equation*}
is available via <me>x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}</me>. (Users from LaTeX will also appreciate that quotes are surrounded with <q> in PreTeXt to handle the different way quotation marks are handled in LaTeX vs most other markup languages.)
You may also have lists withinn paragraphs, ordered <ol> and unordered <ul>, nested as needed. Each list item is represented by <li>.
  • A single item.
  • An item with an ordered list.
    1. First item.
    2. Second item.
Of course, often you have important blocks of content to include, such as <definition>s or <claim>s.

Definition 2.5.1.

PreTeXt is an uncomplicated XML language for describing scholarly documents.

Proof.

Such content is automatically numbered appropriately. Each of the blocks above is structured with a <statement>, and Claim 2.5.2 additionally features a <proof>.
Content is often “knowled”. A knowl is a piece of context-independent information that is useful to transclude elsewhere in the HTML build of your document. For example, in the HTML build for this document, the above proof is knowled by default, and clicking the referenced “Claim” in the previous paragraph expands its knowl to reveal the claim for the reader.

Note 2.5.3.

Because this document was edited directly on GitHub using Codespaces, and served with GitHub pages, finding its source is simple: head to its repository
 1 
github.com/openmathbooks/comat/
and find the corresponding source file
 2 
github.com/openmathbooks/comat/blob/main/source/ch-intro.ptx
. Check the link out to see exactly how each claim, list, etc. in this chapter was marked up!

Section 2.6 Links

In addition to the ability to reference inside a document, such as this one to Note 2.5.3, you can also link to files that you might want readers to download. Here is an example: Fibonacci Excel Spreadsheet
 1 
external/sheets/Fibonacci.xlsx
. Note that this file is stored in your assets folder, and is automatically put in external when pretext build the file.

Section 2.7 Figures and Diagrams

Photograph of a hand tracing over braille code. A cartoon thought bubble contains the quadratic formula in standard mathematical notation, matching the contents of the braille code in the photograph.
Figure 2.7.1. Photograph taken from AIM Press Release on braille, provided as a JPEG in the project assets directory.
A pile of electronic components wired together
Figure 2.7.2. Electronics Diagram generated with Tikz code
Figure 2.7.3. Contour Plot generated from Asymptote code
Figure 2.7.4. Work Cone generated from Asymptote code
Figure 2.7.5. Polynomial approximations of \(f(x)=1/(1+25x^2)\) generated from SageMath code
Figure 2.7.6. An implicitly defined 3D surface generated with SageMath code
Videos can be embedded in PreTeXt documents using the <video> element.
Figure 2.7.7. Big Buck Bunny from “Video for Everybody” Test Page
 1 
camendesign.com/code/video_for_everybody/test.htm

Section 2.8 Interactives

Figure 2.8.1. Right Triangle Paradox powered by Geogebra
Figure 2.8.2. Graph of \(ln(x^2+5)-3\) powered by Desmos
Figure 2.8.3. Intersection of two planes powered by CalcPlot3D
Figure 2.8.4. Implicit Differentiation exercises powered by CheckIt

Section 2.9 Authoring an Exercise

Checkpoint 2.9.1. Manually-authored exercise.

What is \(2+2\text{?}\)
Hint.
We’re being a bit tricky here...
Answer.
\(22\)
Solution.
\(22\text{,}\) where \(+\) is the concatenation operator.

Checkpoint 2.9.2. Using WebWork.

Compute \({1} + {7}\text{.}\)
The sum is .
Answer.
\(8\)
Solution.
\({1} + {7} = {8}\text{.}\)

Checkpoint 2.9.3. Generated by CheckIt.

Consider the following system of linear equations.
\begin{equation*} \begin{matrix} 4 \, x_{1} & + & 3 \, x_{2} & + & 18 \, x_{3} & - & 11 \, x_{4} & = & -14 \\ -3 \, x_{1} & + & x_{2} & - & 7 \, x_{3} & + & 5 \, x_{4} & = & 4 \\ 3 \, x_{1} & + & 3 \, x_{2} & + & 15 \, x_{3} & - & 9 \, x_{4} & = & -12 \\ \end{matrix} \end{equation*}
(a)
Explain how to find a simpler system or vector equation that has the same solution set.
Answer.
\begin{equation*} \mathrm{RREF}\left[\begin{array}{cccc|c} 4 & 3 & 18 & -11 & -14 \\ -3 & 1 & -7 & 5 & 4 \\ 3 & 3 & 15 & -9 & -12 \end{array}\right]=\left[\begin{array}{cccc|c} 1 & 0 & 3 & -2 & -2 \\ 0 & 1 & 2 & -1 & -2 \\ 0 & 0 & 0 & 0 & 0 \end{array}\right] \end{equation*}
(b)
Explain how to describe this solution set using set notation.
Answer.
The solution set is \(\left\{ \left[\begin{array}{c} -3 \, a + 2 \, b - 2 \\ -2 \, a + b - 2 \\ a \\ b \end{array}\right] \,\middle|\, a,b \in\mathbb R \right\}\text{.}\)

Checkpoint 2.9.4. Runestone-powered True/False Question.

    This statement is true or false.

  • True.

  • Feedback goes here.

  • False.

  • Feedback goes here.

Checkpoint 2.9.5. Runestone-powered Matching Problem.

    A multiple choice question
  • right answer 1
  • answer specific feedback
  • right answer 1
  • answer specific feedback
  • wrong answer 1
  • answer specific feedback
  • wrong answer 2
  • answer specific feedback

Checkpoint 2.9.6. Runestone-powered Parsons Problem.

Rearrange the blocks in alphebetical order, ignoring blocks beginning with a number.

Checkpoint 2.9.7. Runestone-powered Matching Problem.

Section 2.10 Not Just HTML, Not Just PDF

This document is available in HTML format at https://stevenclontz.github.io/pretext-getting-started-2023/, and the same document is available in a PDF format at https://stevenclontz.github.io/pretext-getting-started-2023/print/main.pdf.
Obtaining these formats from your source is as easy as running clicking a couple buttons in your Codespace. PreTeXt supports other types of output as well, including Jupyter notebooks, ePub, and tacticle braille code.
You’re encouraged to view authoring in PreTeXt as an investment: you may not need the braille output today, but the little extra thought and care required to author in PreTeXt will allow you to provide this version of your document to a blind student tomorrow.

Section 2.11 Wrapping Up

Go check back on the Codespace you created in Section 2.1. If it’s up and running, you’re ready to move on to the next section!
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