How we ported LaTeX to the iPad

http://texpadapp.com/2012/09/19/latex-ported-to-ipad/

by steeleduncan • 14 years ago

100 36 14 years ago

texpadapp.com

jogloran• 14 years ago

Previously: http://vallettaventures.com/2012/08/27/tex-notebook/

chj• 14 years ago

Developer of TeX Notebook here, now TeX Writer(first native LaTeX compiler on iPad).

That post is no longer true. I wrote the full story here:

http://litchie.com/blog/?p=419

kibwen• 14 years ago

Very interesting, but does anyone here feel like this would be useful to them? For example, in my limited experience with LaTeX I've also needed to generate graphs (via Graphviz or R). Even if there existed apps for these, I'm under the impression that the iPad has no user-accessible filesystem, nor allows iPad apps to talk to each other. Please correct me if this is mistaken.

garrettlarson• 14 years ago

While the filesystem is not directly accessible by either users or apps for security reasons, it is possible for apps to communicate and/or exchange files. Your app can register the ability to open certain filetypes with the OS (e.g., so users can open mail attachments or Dropbox files in your app) and it can communicate directly with another app through custom URL schemes (e.g., to accomplish single-sign-on using the Facebook app).

jdleesmiller• 14 years ago

I can offer one data point: I run a browser-based LaTeX editor (http://www.writelatex.com) and currently 2% of visits come from iPads. 6% come from a mobile device of any kind. I'm not sure how many of those actually try to do any serious writing, though.

RBerenguel• 14 years ago

I installed TeX writer in my iPad (the other iPad TeX version referenced around here in the comments), just for fun (when I needed to do some TeX on the go, I just ssh'd and looked at the PDF in Dropbox.) Finishing my PhD, I don't generate any more images, they are all already done. And TeX Writer is surprisingly effective as a compiler (feels faster than my desktop!) Love it as a proof of concept... but only use it sparingly. I don't think I'd use TeXPad any much, although the editor looks fancier

khaled3• 14 years ago

The most clueless TeX related piece I have read since their previous one. For example, kpathsea is a library that TeX engines call, so no forking is done to “grab search paths from the Kpathsea system”. And the bright future for C implementation didn't happen when TeX WEB code was hand converted into much more readable C code 8 years ago (http://metatex.org/), not to mention the existence of an actively maintained, extended TeX engine written in C (http://www.luatex.org/), wait, this is GPL “encumbered” so it does not count. Did I mention that XeTeX does not “skip the DVI step” at all, but it actually does fork an external binary to convert its ‘extended’ DVI into PDF.

anonymouz3• 14 years ago

I also loved the GPL ``encumbered'' bit. But they are trying to sell a (binary only) app for iOS, so I can see how it's inconvenient to them if other people don't give them all rights to their code.

TeX, while maybe not pretty, has stood the test of time remarkably well. I find it somewhat low of the article to bash the technology it uses (WEB, DVI) just because they are not the newest and hippest.

rmc4• 14 years ago

I also loved the GPL ``encumbered'' bit. But they are trying to sell a (binary only) app for iOS, so I can see how it's inconvenient to them if other people don't give them all rights to their code.

As far as I know, Apple won't allow GPL software on iPad/iOS, they ban it on the App Store. So it isn't this company trying to get around the GPL, it's Apple.

coliveira2• 14 years ago

Agreed. The author displays a huge lack of understanding of how TeX works.

A big problem of current projects to port TeX is that most of them rely in the original translation from pascal to C, which is just a hack turned into a maintenance nightmare. I believe a better approach would be to write a better translator that would be easier to integrate with different environments such as iOS.

mturmon2• 14 years ago

Apparently kpathsea, which is a C library, shells out to implement some functions. That's where their (unclear) comment on forking comes from.

This comment from the previous post indicates that it might not be such a big deal to fix this:

http://news.ycombinator.com/item?id=3264887

The whole thread on their earlier post is here:

http://news.ycombinator.com/item?id=3264341

Alas, it is not particularly enlightening.

timtadh• 14 years ago

So where is the source? Also I am fuzzy on whether or not this is a license violation:

[TeX] This program is copyright (C) 1982 by D. E. Knuth; all rights are reserved. Copying of this file is authorized only if (1) you are D. E. Knuth, or if (2) you make absolutely no changes to your copy. (The WEB system provides for alterations via an auxiliary file; the master file should stay intact.) See Appendix H of the WEB manual for hints on how to install this program. And see Appendix A of the TRIP manual for details about how to validate it. TeX is a trademark of the American Mathematical Society.

I know they are altering the translation not the WEB source but that is still the Tex program.

coliveira2• 14 years ago

I don't think there is a limitation on selling TeX derivatives. A lot of commercial products based on TeX have been created, such as Scientific WorkPlace. I would be concerned about cweb, the translation of TeX from pascal to C used on unix.

khaled3• 14 years ago

AFAIK, the only requirement to comply with TeX license is to not name a the modified program TeX. This wouldn’t be the first proprietary version of TeX.

Too2• 14 years ago

Maybe one of them changed his name ^_^

tomrod2• 14 years ago

I'd like to see a TeX -> MathML program come about. With web publishing, the standard A4 page approach isn't optimal anymore; further, MathML just seems so cool (even if it's still really in it's beta or alpha stages). I know TeX has so many things you can do with it, but this article brings up a great point: with people moving a large majority of their work to diminutive tablets, a 4GB TeXLive distribution probably won't work.

anonymouz3• 14 years ago

The simple answer to that seems to be to not move to working on tablets. For LaTeX editing, I can't see any advantage that a tablet would offer over a notebook, and there are a lot of disadvantages.

tomrod2• 14 years ago

An article that appeared at the same time on HN's front page points out some of the benefits:

http://yieldthought.com/post/31857050698/ipad-linode-1-year-...

khaled3• 14 years ago

There is no shortage of TeX ↔ MathML conversion tools and solutions, one spectacularly prominent example is MathJaX (http://www.mathjax.org/) which can take TeX input and output MathML (for browsers supporting it) or do its own rendering into regular HTML.

Too2• 14 years ago

Mathjax is pretty cool but it's also pretty slow if you have many formulas. While it's loading the page keeps rescrolling up and down because the document grows and shrinks. I started noticing the load after already ~30 formulas, quite big formulas though.

Also the distribution is a bit bulky, it consists of over 30000 files. You can remove many of them but then you also loose a big part of the compatibility. While speaking of compatibility, some formulas look kinda weird, but those are very few

daurnimator• 14 years ago

You had me until "we have begun work on refactoring TeX's translated C sources into C++"

stephen_g• 14 years ago

Why? I know it's popular to not like C++ now but it really is far more maintanable for a large project than C - best example is how GCC are moving to C++ for the compiler source.

jedberg• 14 years ago

I wanted to try the demo, but I'm not sure what to do with it. I loaded up my resume, but since typesetting is disabled, what exactly am I "demoing" other than an input field?

Narretz• 14 years ago

It's great they did it, knowing how frustrated they were in the last blog post. That I don't really understand what's going on only makes the achievement larger in my eyes. Would be awesome if this led to a faster tex version that can be used by Desktop applications too, like Texmaker etc.

languagehacker• 14 years ago

I really hope that this Bataan death march of porting LaTeX to the iPad is the final word on whether or not literate programming is a worthwhile endeavor.

mturmon2• 14 years ago

It doesn't have to do with literate programming per se.

It has to do with a very widespread and powerful legacy system (with extreme requirements for backwards-compatability and portability) that happened to be written decades ago in, basically, Pascal.

Furthermore, the people doing this port don't seem to have total command of the tex infrastructure. This has held them back.

For instance, they didn't know what kpathsea was until well after they started their port ("As best we could tell kpathsea is a library to find fonts and scripts in the sprawling TeX distribution...", from http://texpadapp.com/2011/12/10/price-of-amessy-latex-not-fo...).

kpathsea is a basic library that anyone who has tweaked TeX configurations would know about. It has a certain syntax for subdirectory searching that you have to learn, as well as a utility command (kpsewhich) that you run quite a lot to debug "file-not-found" problems.

microtherion• 14 years ago

Knuth's Web literate programming system is based on transforming the literate sources two different ways: "weave" transforms the source into the published book form, and "tangle" strips all comments, and massively rearranges the source into compilable Pascal (Rearranging was probably a somewhat Pascal specific feature, and newer literate programming systems don't necessarily rearrange anymore, I think).

Since their C code is based on the tangled code, their transformation discards the ENTIRE comments of the original source (and simply not stripping the comments would not help, because in the rearranged order they wouldn't make much sense anymore). Essentially, they are rendering TeX illiterate.

I can't conceive how this could possibly lead to a more maintainable product. TeX has a perfectly workable way of making arbitrary local changes through "Changefiles". The Pascal/C code was never meant to be edited directly.

sitharus• 14 years ago

I was almost going to buy that app, but it looks like their modified tex engine isn't open source.

I'm not quite sure why this irks me so much. I'm not likely to mess with tex source, but it'd be nice to share what was shared with you.

How we ported LaTeX to the iPad

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