The iPad's application library grows to encompass more and more functions that were previously the domain of personal computers. One of the more recent additions to this category is a classic documentation markup language called TeX. TeX Writer offers on-board compilation and display of TeX markup. Read on to learn how well this computationally intensive conversion task performs on the iPad.

Created by the legendary computer scientist Donald Knuth, TeX allows individuals to include instructions in their plain text files that will render a variety of text and imagery, especially useful for properly rendering complex mathematical formulas.

Unlike other TeX syntax-aware editors available in the App Store, TeX Writer has its own on-board code compile and results display. It does not require a remote server or need to export the edited TeX files to be saved to PC for compilation and file output. For those who have learned the intricacies of the TeX markup language, this is big news. Unfortunately, there are a few problems with the current version of TeX Writer that make it a work in progress.

Beyond the built-in TeX interpreter, TeX Writer offers a few nice features such as an extra keyboard row of frequently used TeX markup characters, built-in drop box support (file upload/download - no sync yet, though this is coming in a future update of the program), and a choice of 4 different background display color schemes for showing the rendered TeX documents.

While the program achieves its advertised goal of TeX document conversion and rendering, it does not export the rendered document to any transferable file type such as PDF, Word or even a PNG screenshot. Heck, it doesn't even offer the option send the output to an Airprint-compatible printer.

Second, while the extra row of keys is a nice timesaver, the editor in TeX Writer is definitely no Textastic. In fact, TeX Writer's editor doesn't even have a Find feature - very annoying when trying to locate that misspelled tag that prevents a TeX document from compiling.

It's also buggy. Little things like TeX Writer strangely shrinking the top half of the edit window in landscape mode to half its size after compiling a TeX file. Correcting this bug requires you to shift to portrait then back to landscape. I also had TeX Writer crash several times during the compile cycle, especially on large or complex TeX documents. Several of the examples on the TeX Showcase website wouldn't even compile or required numerous changes before they did.

According to developer, a big update is coming soon that will add support for Dropbox sync folders, the ability to import additional required LaTeX packages and show JPEG and PNG file previews. The update promises to address several minor bug fixes as well. So there is hope that TeX Writer will eventually become a stable, reliable product that rivals what currently requires a PC to accomplish. But in its current state, TeX Writer offers only the very basic functions to convert simple TeX documents from markup to final display output.

Developer: FastIntelligence
Price; \$9.99
Rating: 3 out of 5 stars

****** UPDATE: September 13, 2012 ******
FastIntelligence just released version 1.2 of TeX Writer that adds the ability to export TeX documents to PDF, finally taking the app out of the 'neat demo' category into the 'usable' category. While this much needed feature works, it's not as tightly integrated as I expected. PDF's are generated automatically from a well-formed TeX compilation cycle, whether you want one or not. And you also can't view the generated PDF's within TeX Writer. Instead, clicking on the generated PDF (which has the same base name as the source TeX file, plus the PDF extension) will pop up an "Open In..." dialog box, allowing you to send and open the PDF in your preferred PDF reader (such as iBooks). While I would have preferred to view the PDF within the TeX Writer environment itself, it's at least a big step forward for TeX authors looking to compile and render TeX documents that can be easily shared with other people.