In our January 2011 issue, we examined the three most popular e-book readers and iPad apps—Kindle, Nook, and the Borders Reader. We found them (at that time) to be seriously lacking in their abilities to display mathematics textbooks properly, and we placed the blame squarely with the publishers’ near-unanimous insistence upon formatting their books in the readers’ .AZW or .EPUB formats. We decided to look at mathematics e-books again to see if anything has changed. We included in our more recent experiment the author’s new iPhone 5 to see how maths ebooks look on the “little screen.”

Since our original editorial, a few things have changed. Perhaps the most significant change is the advent of the Google Play app for iPad. Google Play is a “game changer” for the world of mathematics and physics e-book publishing. At least Google has managed to preserve the integrity of LaTeX’s beautiful typesetting; still, Google’s app is not without its quirks, as we discuss below.

In the spring of 2010, Amazon's sales of e-books surpassed its sales of hardback books. This is not surprising when one considers the prices of hardback books. Then in December, 2010, sales of e-books through Amazon overtook its paperback sales. This indicates a major change in the way that the world reads books. Academics have been at the forefront of this change from print to electronic documents. For more than a decade, it has been standard for academics to share preprints of articles via e-mail or Arxiv. Most of us use some sort of LaTeX implementation to produce our journal articles and lecture notes. Then we simply distribute the DVI or PDF files to the world.

Unfortunately, most academics and students then print on paper the files they receive because it yields the most readable and portable document. Few—if any—have the will power to read an entire 35-page journal article on a computer monitor, and until two years ago there did not exist a portable device which made it easy to read an electronic version of an article or textbook, especially one with a significant amount of mathematics in it.

With the tremendous rise in popularity of various e-book readers such as the Kindle, iPad, Kobo Reader, Nook—to name only a few—textbook publishers have begun to make their titles available as e-books. DSWeb's book reviews editor tested e-books from some of the biggest mathematics and engineering textbook publishers. We tested e-books on five devices: the Apple iPad, Apple iPod, the Apple iPhone 5, the Nook Color, and the Motorola Droid A-855. For the Apple products, we used apps created by Kindle, Google, Barnes and Noble, Kobo, and Bluefire.

Google Play

The Google Play app is “hands down” our winner. It is the best way to read a mathematics book on your iPad, iPod, iPhone, or Android device. We tried a number of books—both mathematics as well as fiction books—and Google Play displayed them all in both a very readable and aesthetically pleasing format. For most books, the Google Play app gives the reader the option to display the scanned pages of the book, instead of the standard flowing text format. In fact, for some mathematics books, it is only possible to view the scanned pages.

As one would expect, the “scanned pages” format of the ebook allows the reader to read the book as the publisher intended it and exactly as LaTeX produced it. It is as if someone made a blemish-free photocopy of the original pages of the book. It also preserves the pagination of the original book—something which other book readers do not.

Google Play has not yet been updated for the iPhone 5, so the app will not yet allow you to rotate the display; however, we expect an updated app to come sometime in the near future. Still, reading a mathematics text on the iPhone 5 in the “scanned pages” format was very pleasant. Since testing the Google Play app, our book reviews editor has started buying all his ebooks for Google Play.

Google’s Play app isn’t without its annoying problems. Occasionally upon startup the Google Play app insisted that it must update the contents of the the e-books on our device. This required a live internet connection, and the app did not give us the option to cancel or delay this update when we did not have an internet connection. Although this did not happen every time, when it did happen it made the Google Play app unusable for reading any books at all until an internet connection could be found. This is not a problem which we experienced with any other e-book app. A phone call to Google’s technical support about this problem was equally frustrating. The tech support specialist simply kept reiterating that a “live internet connection is required in order to update any software on your iPad, sir.” Well, we’re glad that they clarified that. Neither the Kindle app nor the Nook app had this problem. They seemed to update content when the device has a live internet connection.

Our editor was planning to read an e-book or two during his 18-hour flight to Sri Lanka this January, but this little quirk in Google Play is forcing him to make back-up plans. One hour into a flight to Bandaranayake would be the worst possible time for Google Play to decide that it will not proceed until it has updated its library on the iPad.

Still, despite this not-so-insignificant quirk, our editor has started giving his students the option to purchase the Google Play e-book editions of textbooks adopted for his classes. We shall say a little about pricing at the end of this article.

Our verdict: Google Play is the best way to read mathematics e-books, just don’t count on being able to use it in a place where no live internet connection is available.

Kindle

Our first test in January 2011 used Rufus Bowen's classic text Equlibrium States and the Ergodic Theory of Anosov Diffeomorphisms, [Bow08] which was meticulously retyped in TeX and republished by Springer in 2008. We tested this book again recently on the Apple iPad, iPhone 5, and the Motorola Droid, using the Kindle app on all three devices. Sadly, nothing has changed. These devices rendered the book well, but it certainly was not TeX-quality formatting. The in-line mathematical symbols were displayed neatly and correctly with the proper size relative to the surrounding text, but some subscripts and superscripts were slightly washed out or totally lost; furthermore, this was completely independent of the device since the defective subscripts were rendered in exactly the same way on the iPad, iPhone, and the Droid. Curiously, we found that increasing the font size made this problem worse, with even more subscripts vanishing!

Our second test of the Kindle app used Global Riemannian Geometry: Curvature and Topology [MM03] by Steen Markvorsen and Maung Min-Oo, published by Birkhäuser Verlag in 2003. The results were not impressive. Even plain text rendered horribly on the iPad, iPhone, and the Droid. While the "old-fashioned" bound print copy would certainly be a good book for one to have as a reference, reading the e-book on the Kindle app would test anyone's patience. The text looked as if someone photocopied the original book on a very cheap photocopier, and then made another copy of the bad photocopy. Every letter on every page washed out a bit. Even the umlauts were missing from "Birkhäuser" on the title page!

Our verdict: Kindle ebooks are not yet a viable way to purchase mathematics or physics e-books. Some books are readable on the Kindle app, but most seem not to be ready for release as e-books yet. If the option is available, try the free sample available from Amazon before deciding whether to buy the print copy or the e-book.

Nook

The results for the Barnes and Noble Nook were just as unfavorable as they were for the Kindle. The first book we tested was Ruey S. Tsay's Analysis of Financial Time Series, [Tsa05] published by Wiley and Sons. We tested this book on the iPad, the Droid, and a Barnes and Noble Nook Color. On all three devices, this book was very readable. Both plain text and equations were rendered very clearly. In-line mathematics symbols were generally the same size as the surrounding text but they were not aligned vertically with the rest of the line. Centered equations were smaller than the regular text, but all characters—including subscripts and superscripts—were clear and complete. Both centered and in-line equations appeared as though they had been converted into images. It was reminiscent of the old LaTeX2html that we all know and love from our Netscape Navigator 1.0 days. While not as aesthetically pleasing as the print copy, the e-book version for the Nook was certainly every bit as readable as the print version.

Our second Nook e-book was Raymond M. Smullyan's Gödel's Incompleteness Theorems [Smu92]. Plain text was displayed perfectly. Small in-line mathematics symbols were difficult to read, but this was corrected by increasing the font size.

Our verdict: Barnes and Noble's Nook does not produce a nice mathematics e-book; however, books are quite readable on the Nook Color and on the Nook apps. If the option is available, try the free sample available from Barnes and Noble before deciding whether to buy the print copy or the e-book.

Other readers

Since the publication of our first editorial in January 2011, Borders has (sadly) since gone out of business, so we tried some other readers which have stepped in to fill the void.

Bluefire and Mardel are two readers which are capable of displaying books in PDF format, but they require a separate Adobe DRM (Digital Rights Management) account in order to transfer the content to your reader or to your iPad. One advantage of the use of Adobe DRM is that the reader can borrow books from a library. The disadvantage is obvious—the need for a separate Adobe DRM account.

Google Play does not require a separate Adobe DRM account.

Our conclusions

Publishers seem to be intent upon selling their e-books in Amazon's AZW, Nook's PDB (eReader), or ePub formats, which are fine for books written only in plain text. Mathematicians, physicists, engineers, chemists, etc., have become accustomed over the last few of decades to writing documents with LaTeX and reading documents created by LaTeX and rendered in PDF (portable document) format. Beginning with Donald Knuth and continuing for 40 years now, a very large group of mathematicians, computer scientists, physicists, engineers, chemists, musicians, and many others have worked to expand upon the power of the TeX engine to produce beautiful documents.

Book sellers and publishers seem intent upon taking us back to the pre-TeX years. Young music listeners might have given up on audio fidelity by listening to lossy mp3s on iPods, but mathematicians will not happily give up the beautiful formatting which LaTeX has brought the world. We will not return to the old days of LaTeX2html.

In our view the solution is simple: publish mathematics texts in PDF format. All of the readers currently on the market, except perhaps for the Azbooka WISEreader, support the PDF format. So why are publishers, even the big mathematics publishers like Springer and Birkhäuser, avoiding the PDF format? Some publishers—Taylor and Francis, for example—are making their e-books available in PDF format so that they read naturally on the screen of an iPad or computer, but they can be difficult to read on an iPod or a smart phone because the flow of the text across lines may be unnatural. (This is a function of how the PDF file was created.) Most of us probably create our PDF files using pdflatex or dvipdfm. Files created in this way are not easily read on small-screen devices such as the Nook Color, the iPod, or smart phones because lines do not wrap correctly. The screens of the Apple iPad and the larger ebook readers, though, make them quite sufficient for reading PDF files created by dvipdfm or pdflatex.

In short, it seems that publishers have made the decision to sacrifice the quality of the reproduction of mathematics symbols in return for good line wrapping. They have dispensed with one aesthetic quality in favor of another which is presumably more valued by those in the publishing profession. We in the sciences, though, feel that this compromise need not be made. Publishers and e-book reader developers are trying to reinvent the wheel; in this case, they are trying to reinvent PDF. Perhaps Google and its Play app will rescue us from downward spiral into the lower rings of the publishing world’s Inferno.

Our final word is about e-book pricing. All of us have probably had in our offices that publisher’s representative who insists that the new edition of our calculus textbook costs \\$218.95 because the used textbook market is driving up the prices. Who among us hasn’t heard that argument? (In a recent compensated review for a major publisher, our book reviews editor said that “no textbook should cost \\$218.95 unless it has been copied by hand onto parchment.” He probably won’t be asked again to review any new textbooks.) Some mathematics e-books cost in excess of \\$500! For many major publishers, the e-book version (if it is available) comes in at around half the price of the hardcover, but for many the e-book costs nearly the same as the print edition. It is our opinion that e-books are still far too expensive. The advent of e-books should have brought textbook prices down, but this has not been the case. This is why many of us have moved to distributing our books freely via the internet or through on-demand publishing companies such as Lulu or University Readers.

[Bow08] Rufus E. Bowen, Equlibrium States and the Ergodic Theory of Anosov Diffeomorphisms, 2nd ed., Lecture Notes in Mathematics 470, Springer Verlag, 2008. (Republication of the 1974 edition.)

[MM03] Steen Markvorsen and Maung Min-Oo, Global Riemannian Geometry: Curvature and Topology, Birkhäuser, 2003.

[Tsa05] Ruey S. Tsay, Analysis of Financial Time Series, 2nd ed., Wiley Series in Probability and Statistics, Wiley-Interscience, 2005.

[Smu92] Raymond S. Smullyan, Gödel's Incompleteness Theorems, Oxford Logic Guides, Oxford University Press, 1992.