## Introduction ##
Those who have read my previous posts will not be surprised that I am writing this in LaTeX. Nor that I am writing this on my iPad. I’ve done both before. What is different this time is that I can *compile* the document on my iPad (“Look Ma! No cloud.”) to see what it will look like[^1].
This is thanks to a new iPad application called [TeX Writer (UK store)](https://itunes.apple.com/gb/app/tex-writer-latex-editor-compiler/id552717222?mt=8).
## The Backstory ##
I learnt of this application through an answer to a question on the main site, unsurprisingly [Is there a (La)TeX distribution running on iPad?](http://tex.stackexchange.com/a/68427/86). It came with the warning that it only ran plain TeX, but undeterred I downloaded it. As well as my general enthusiasm for all things TeX and iPadical, I thought it would be enough to be able to run plain TeX. Thanks to the main site, I’ve seen enough of plain TeX not to be scared of it and I thought it more likely that I use the iPad for little things than my usual 50 page article, so plain TeX might well suffice.
Wanting to share my experiences, I asked on the site for some advice on how to begin ([Now that I can run TeX on my iPad, what shall I TeX?](http://tex.stackexchange.com/q/68436/86)). Unfortunately, almost all of the answers didn’t work due to memory limitations of the application. At this point I found the [developers’ website](http://litchie.com/blog/) and started making a nuisance of myself there. The conversation shifted to email and I got invited to be a beta tester.
The next version has now been released and there is a development plan so I can talk about it at last!
## Is it TeX? ##
As I don’t have commandline access, I can’t run the trip tests, but as far as I can tell then it is TeX running natively on my iPad. No cloud, no emulator. Given the plethora of posts on the internet opining that this Could Not Be Done, I am reminded of the quote:
Someone saying a thing cannot be done is liable to be interrupted by some damn fool doing it.
(Sadly my source for that quote is inaccessible to me for a year. The versions I find on the internet don’t have the “damn fool” which, I think, changes the tone considerably.)
However, it is not (yet) e-TeX, LuaTeX, or XeTeX. Moreover, output is DVI, though it does then convert it to PDF which can be exported to other applications. So it might be a while before I write a TikZ answer on my iPad! The developer is thinking about these things, though, so check the latest version for the latest features.
## TeX, the Whole TeX, and Nothing But the TeX ##
There’s more to writing beautiful documents than the TeX program. There’s the formats, packages, editor, output type, output viewer, …. The application comes with the program, formats for plain TeX and LaTeX, a number of packages for LaTeX, an inbuilt editor, and a DVI viewer. The document directory can be linked to Dropbox. So that makes it possible to get documents into the application. The TeX file is synced so you can get that out of Dropbox after editing. As I said above, upon successful compilation then you get a PDF which can be shared in standard iPad ways.
The application comes with a set of packages. There’s a size limit so it won’t be possible to put the entirety of TeXLive in it, but fortunately it isn’t necessary as the developer has set aside a particular sub-directory of the “documents” directory as a place to put other packages[^2]. These can be uploaded via Dropbox, but it choked on the 10,000 or so files I tried. Fortunately, filesystem access is not hard to come by (even without jailbreaking) and, frankly, for uploading all the actual files from TeXLive then this is a more reliable route.
So I have TeXLive 2012 and can run anything. Almost. There’s still the fact that it doesn’t have the e-TeX extensions. And the memory isn’t enough yet to run `beamer`. It is enough to run TikZ, but the DVI output doesn’t show it, nor does the conversion to PDF. So I can’t yet compile my seminars on it, but I can do lots of other fun stuff.
The developer tells me that the editor is a big focus for development right now so I won’t say much about that except to say that the initial signs are encouraging: There’s an extra two rows above the standard keys with things like the backslash and braces, and – crucially – left and right cursor keys.
## So What Is It For? ##
It is TeX on an iPad, natively. The question is, what is it for? How often do you find yourself wanting to run TeX on your iPad?
The answer depends somewhat on how you view your iPad. Is it a slimline computer or is it an oversized phone? I had a few promotion codes for this application and one of the people I offered one to said, “No thanks, I only use my iPad for checking email and browsing the web.”. Clearly in the second camp. But despite my iPad having been bought me as an eBook reader, I’m in the first camp so I’m always interested in things that make my iPad able to do more computer-like things.
A big driver of this for me is related to something I see a lot on our [Photography sister site](http://photo.stackexchange.com/). They have a saying:
The best camera is the one you have with you.
I’ve learnt the truth of that in photography, and I think that the same thing is true of computers. When travelling, it is much easier to just take my iPad than to lug a laptop as well. And there are definitely occasions where an iPad is *better* than a laptop (taking notes in a seminar, for example) so given the choice I’d rather just take the iPad. This application means that I can still work on my TeX documents while travelling.
It may be a while before I write an entire article on my iPad, but it sure would be useful to be able to make last minute changes to a presentation. Just need a smidgeon more memory to run `beamer` and I’ll be happy.
Indeed, my one real difficulty with this application isn’t a difficulty with the application but with entering text on an iPad in general. At last there is an application where I want to be able to type quickly. But “touch typing” on a touch screen is not the easiest thing to do. My error rate is still rather high. Maybe I’ll get a bluetooth keyboard, just so I can use this application.
So, the verdict. Definitely worth keeping an eye on. For the price, I’d say it’s worth buying. It does have limitations, but it is also under active development and I’ve found the developer to be very responsive to feature requests.
It’s TeX on an iPad. Just a shame that someone else thought of the name iTeX already.
[^1]: Though as it will actually get translated to Markdown for inclusion in the blog, it won’t look as good in its final form as it does now.
[^2]: The directory is `texmf-local/TeXinput`. At present, there is no recursive search so the files all need to be in this directory.