Doing the Math

Sometimes it is interesting to have equations in an e-book. Of course if it is a book on mathematics, but also in other books. I made an attempt to include equations in the book Into Programming, like this.

For the web version of the book, I used MathJax, a Javascript libary that allows you to write the equations using LaTex notation. As an example, the following html code

$$
a_n = a \prod_{i = 1}^n \left (1 + \frac{p_i}{100} \right )
\quad \quad \quad (5)
$$

can be used (together with the appropriate script tag to include MathJax) to create an equation. You can see the equation as equation number 5 on the About page for equations in the book Into Programming.

For the epub- and mobi-versions of the book I used images. I did not expect the typical e-book reader software of today to handle MathJax yet. The images are created from LaTeX, using a similar notation as for the MathJax, and each equation is put into its own LaTeX file, e.g like this

\documentclass[b5paper, 9pt]{memoir}
\usepackage{amsmath}
\pagestyle{empty}
\begin{document}
\begin{displaymath}
a_n = a \prod_{i = 1}^n \left (1 + \frac{p_i}{100} \right )
\quad (5)
\end{displaymath}
\end{document}

Then, images can be created, one for each equation, using LaTex and the tool dvipng.

You can see the result, in the e-books, in the Chapter called Again and Again. The books are found, as epub and mobi, on the Books page.

Update on epub-readers

Here is a summary of the current status regarding epub-readers suitable for the book Into Programming.

The following readers have been tested Ok on an iPad 2:

• The Bluefire reader. In contrast to what was said in an earlier post, external links are now supported in Bluefire for iPad, resulting in a quite nice reading experience.
• The iBooks app.

For the iPhone, the book opened fine in the Stanza reader, but unfortunately not in iBooks for iPhone.

The following readers have been tested Ok on an Android phone:

• The Aldiko reader.
• A reader app called just that, Reader. It was pre-installed on my HTC phone, and I am not sure if it can be found in the Android Market (nowadays known as Google Play).

Links to the book are found on the Books page.