eBook readers for mathematics For a while I have been eying stand-alone eBook readers that use "electronic ink" displays, the most popular ones seem to be the Amazon Kindle readers. 
My criteria are as follows: It should be able to display pdf's and math formulas in them just like they were printed and they should be able to handle "big files", say the numdam versions of EGA (even with my desktop browsing them is noticeably slower than browsing other pdf's).
A nice but not strictly necessary feature would be the ability to read djvu files.
Does anyone here have experience with these kinds of devices? Does anyone use them in their mathematical work days? Do they make things easier?
 A: I have a Kindle DX and use it for this purpose. As Xandi noted, the smaller Kindle 2 can now read PDFs, but its screen is too small to be usable for A4 pages or most technical books. However, the Kindle DX's screen is fine for such usage, at least for my eyes.
As for DJVU, the Kindle has no native rendering support, so I always use the command-line DJVU-to-PDF converter that comes with DjVuLibre.
The downside of the Kindle DX is the price tag and the greater weight compared to the Kindle 2. But compared to lugging around 500-page technical books, which was the primary replacement role for which mine was purchased, it's light as a feather. 
A: Just came across this old question and thought I would add my recent experience.  After my iRex iLiad gave up the ghost, I got an Onyx Boox M92 (U.S. distributor here) and I am very happy with it.  The screen is large enough, and the "hide margin" zoom setting works well enough, that I have never encountered a math PDF that I have been unable to read in that way.
(Those dratted computer science papers that are written in two columns with tiny font, on the other hand, are a little trickier.  For that you can flip the whole thing into landscape mode.)
It is not finger-touch sensitive, but has a stylus that lets you make handwritten annotations on PDFs, then save a new PDF including the annotations.  I use this a lot for editing my own work: I read it and make notes on the Boox, then export the PDF back to my computer where it is easier to flip through as I am making the changes.  (One of the main downsides of an e-ink reader is the relative slowness of page turns.)
I don't end up reading DjVu files very often for whatever reason, but it does seem to read them fine.  It is sometimes a little slow in loading a large file; I haven't tried any extremely large ones.
I do find that reading in e-ink with reflected light is noticeably more comfortable, and perhaps faster, than reading on a computer or tablet screen with radiant light.
A: I use PocketBook Pro 902 and very happy.


*

*It reads and rescales djvu and pdf. 

*Cross-references in pdf do not work. (Maybe it is fixed in 903).

*There is no build-in way to crop margins for pdf/djvu [it is only matter if margins on the left and right are different].

A: Hi, I have been using the new Kindle (dimensions: 166 mm x 114 mm x 8.7 mm) for a week; here are my observations. It does read mathematics texts written in pdf, hence arXiv papers. I noticed only one issue which concerns margins and the font size. Indeed, most mathematics textbooks and papers have big margins, and then not look good on the Kindle. There is however the possibility of zooming, but as mentioned above, this is very disturbing since then one can no longer see the entire page one is reading. Another alternative is to convert pdf or djvu to e-reader formats such as mobi, rtf, etc. by using a program such as Calibre (for Linux distribution); but then one gets some ugly extraterrestrial maths formulas.
Here is the solution I have been adopting so far to read arXiv papers: I download the .tex files, and fiddle about with the margins and font size; more precisely, the reasonable font size is 12pt, I cut almost all the margins and enlarge the lines (this is useful especially when one deals with big formulas or diagrams) by adding "\usepackage[paperwidth=16cm, paperheight=20cm,top=0.5cm, bottom=0.5cm, left=0.5cm, right=0.5cm]{geometry}". The result I get is much better, and I can read without trouble ... just imagine one of the printed two pages on an A4 sheet.
A: iPad is good for pdf and djvu (and only for that). But you can't reed your favorite mathbooks on a beach, because its display is not e-ink.
A: I would like to add that if you have access to the TeX-like source code, probably LaTeX, there is usually a good solution. For example, you want to read preprints fetched from arXiv of which you can download LaTeX source code. In this case, you can have a try to take advantage of tex4ebook, which compiles LaTeX source code to epub and mobi ebooks which you can send to ebook readers like Kindle.
The easiest command to compile is:
tex4ebook -f epub+dvisvgm_hashes [filename]

or you replace epub by mobi if you want to compile a Kindle ebook (you need kindlegen for that). dvisvgm_hashes is used to generate svg, Scalable Vector Graphics, pictures for equations etc, better than png pictures. It does not work perfectly, but usually with a bit of hacking and modification of the LaTeX source code, I can get an ebook file. I sent hundreds of papers and lecture notes to my Kindle, and it works for me.
A: I will throw in a response for Sony Reader Daily Edition.  It's not perfect by any stretch, but it has some advantages over Kindle:


*

*It reads pdf, not djvu (yet), as with Kindle. 

*It has a feature which automatically zooms to margin, which is very important for latex documents with wide margins.

*It has landscape viewing, like Kindle.

*It has a touch screen, which unfortunately adds a glare to the e-ink because of the plastic laminate sensor over the screen.  On the other hand, I find it prohibitively frustrating to try to navigate a pdf document without the touch screen, so it's worth it for me.

*It has a very rudimentary sketch program, about as useful as a post-it note in terms of what you can write on it, due to poor sensor resolution.  Still it comes in handy in a pinch.


All in all, it's perfect for reading a paper straight through, probably as good as one can hope for quickly jumping around a document (though more annoying than a computer or actual printout), and convenient for storing many articles.  It acts like a thumb drive on other computers, so no need to install any software to load pdfs onto it.
A: I bought a pocketbook reader 602 recently, and I think it's great.
http://www.pocketbook-usa.com/support/pocketbook-602/
With the exception of a few files (I had to cut out some of the white margin), I can read them no problem. A couple of my friends complained about the small screen size, but I don't have any issues with that. Some complained about the fact that it wasn't touch screen, but then, I didn't want a touch screen.
It's a bit pricier than the Kindle, but I honestly didn't like the kindle too much when I tried it out at Bestbuy. In fact, I got to try a number of the e-readers there, but none of them seemed that great.
I have a more detailed post about the PBR602 on
https://math.stackexchange.com/questions/7514/kindle-as-a-tool-for-mathematicians/
A: With any reader, you may use k2pdfopt to convert the pdf to appropriate size, rearrange/reflow lines, etc. Works quite nicely on arxiv'd articles.
A: For math books you probably need to look at larger devices (8" or 9"):


*

*iRex DR1000s and DR800SG (am not if sure the company still exists) 

*The new Kindle DX Graphite

*The iPad (not a reader, but it's here)


However, I find that 6" devices are more portable, unlike the (bulkier?) 8" or larger screens. But having a smaller screen means less screen estate and the PDF format cannot re-flow correctly because the page layout is designed for a specified size and is constrained by graphics and positioning of other elements. This means that what you see on the screen is a smaller version of the page, sometimes not easy on the eyes or downright illegible. The solution is to read in landscape mode and, if possible, to cut the page margins in the PDF.
For PDF and Dejaview formats take a look at Pocketbook 301+. In my opinion, this is the best PDF reader in the 6" class. There is a newer model (Pocketbook 302) but it has a glossy touch screen, so I would avoid that. I use it mostly for technical documents, heavy mathematics with graphics and it's great because:


*

*Zoom to arbitrary level and keep the zoom between page switches (persistent zoom)

*Landscape mode with automatic margins cut

*Multiple-column mode (great for two columns papers in A4 or Letter size)

*Two PDF viewers (XPDF and Adobe with DRM support) and an excellent DejaView viewer.


The PB301+ is a EB600EM clone with 8 gray scale levels (revised in 2009). Do not mistake it with other EB clones (there is a gazillion of them): the firmware is what makes Pocketbook a great PDF viewer and you cannot install it on other clones.
Concerning larger device: there is a number of them arriving soon on the market, including the Pocketbook 901 (9.7" screen size) expected in September 2010.
Beware of the touch screens: they reflect a lot (screen glare). I owned a Sony PRS600 but I had to send it back. I really wanted this to be a non-issue, but the glare and the reflections ended by getting in my way when reading: I needed a constant conscious effort to not see the reflection of my face in the device, all this combined with a sort of "fuzzy display" due probably to the "through the glass" effect induced by the screen.
On the web, the mother-lode site of mobile readers is http://wiki.mobileread.com (the technical descriptions are here: http://wiki.mobileread.com/wiki/E-book_devices). The forums are a good source of personal opinions.
Now, surprisingly, reading mathematics on a 6" screen turned out to be a much better experience than I have thought. This is subjective, but again, I expected worse. Here are some of my impressions (for a PB301+, 6" screen):


*

*Landscape mode is OK: you will see one third or half a page at a time but you can switch quite fast, up and down, in the same page

*Page turn is slower (1 sec), so turning pages back and forth is not practical. You can jump directly to any page but you will have to type the page number... not very practical on a device without keyboard

*Bookmarks are great and allows you to jump anywhere in the document.

*Reading is just like paper, not very stressful for the eyes

*Some documents are just too small even on maximum zoom in landscape mode


Good luck with your choice!
A: Check out the Entourage Edge. It's a dual-screen e-reader; one screen is a 9.7 in. e-text display and the other is a 9.7 in. LCD display. The e-screen has a very nice highlighting/annotating system and will displays the table of content for a pdf while you're reading it on the e-screen so that you can jump around in a book or search for previously highlighted passages. Really, having the lcd screen is what sets it apart because you gain a lot in functionality over the other single-screened e-readers. Not to mention it runs on android, and has built-in usb, webcam, and microphone for other educational purposes.
A: Added this as a comment, (and to be honest haven't used it), but there exists a tablet netbook that may be good for the job
http://www.amazon.com/Asus-T101MT-EU17-BK-10-1-Inch-Convertible-Tablet/dp/B003D1DZBY/ref=pd_cp_pc_1
A: I have now a good library of math pdf books on my iPad. I use GoodReader app, that offers wonderful features like cropping the pages, so they fit well on the screen and you haven't to zoom in and out all the time, and I read a lot of PDF with that.
For a good experience, the PDF must have already inside the table of contents, so you can jump easily from a chapter to another, but often pdfs don't have it, so I have to add it to them manually with adobe acrobat.
A: The first post of this thread is quite old (it was posted more than 1 year ago). 
In the meanwhile, new ebook readers appeared on the market (both Kindle 3 and 4 have been announced in the meanwhile).
Is anyone able to provide an up-to-date review of these new ebook readers? In particular, I'd like to know how these readers behave with books in djvu or pdf formats, and articles in pdf format. I believe that the new devices are much faster in dealing with pdf or djvu than the older ones, isn't it?
Thanks!
A: I tested the smaller version of Kindle a year ago or so - it really did not work too well. Kindle now supports pdf (that was not always so), and memory can probably be upgraded ad infinitum. The real problem is quite stupid, namely that there is no zoom-function. Rotating the page by 90 degrees and thereby displaying half of an A4 page is the best Kindle can do, and that leaves the text still awfully small. Reading text is already uncomfortable, reading a formula with a double superscript is impossible. This is especially frustrating if one third of the page witdh is occupied by margins.
A: Another page for taking a fair look at the eReaders market is
http://www.ereaderguide.info/
They do extensive reviews of the machines and rate them by several criteria. If you go into the page of a particular eReader, you will see which file formats it supports (e.g., you can see that, in fact, the EPocketBook 301 supports DJVU!) and also a long, detailed analysis about how good it is for reading.
(The page looks like a little biased towards Amazon and their Kindles, though).
I recommend you navigate this site for a while before making your mind up!
A: I have a Sony PRS-505. It works reasonably well for reading straight through, but is too slow for jumping around comfortably. It can read PDFs directly, but cannot zoom (increasing font-size will reflow the text to fit the margins which actually works pretty well for text only PDFs but messes up formulas and diagrams). You can rotate the view 90 degrees which leaves the text a decent size provided you chop off all the margins before putting the PDF on the device. Adobe Acrobat (full Acrobat, not the Reader) can do this, or a variety of commandline tools: on Linux you can use pdfcrop, pdftk or pdfmanipulate (that last one comes with calibre), a windows program called soPDF I found on some ebook forum, etc. Removing the whitespace in the margins really improves the experience, and should probably be done with any of the current eBook readers: even the ones with zoom will probably zoom very slowly.
A: I use IPad as an ebook reader with iAnnotate, which allowes to annotate the PDF files, and I am ver pleased. 
A: i was also using the Kindle reader for reading the Ebook, but this 6" device was not able to read some technical books related to my Engineering subject. i tried so many converters to make it readable but none of them helped to achieve the same. After several hours of search, i finally found this thread (http://forums.techarena.in/portable-devices/1455402.htm) which helped to solve the problem.
A: I would recommend any device on which KOReader runs. These currently include Android, Cervantes, Kindle, Kobo, Pocketbook, ReMarkable and desktop Linux. (Some of them require first a jailbreak before KOReader can be installed.)
KOReader is a viewer program for all the common e-book formats, but I will here describe only its PDF viewer, because this is most important for mathematicians. And the PDF viewer is much more powerful that all the built-in PDF viewers that I know. It has the following features (among others):

*

*Easy cropping, in a semi-automatic or an automatic mode. One can remove page margins and display only the text of a PDF file.

*The cropped pages can be arranged in a continuous flow.

*KOReader can handle multicolumn texts reasonably well. It then only shows a smaller region of a page, containing part on a single column, and when one requests the next “page”, the displayed region moves in the right way.

*The display of the text can be rotated by 90°, which helps when a paper has rather long lines.

*Text can also be reflowed, and mathematical formulas are preserved. (Reflow does not always work well, but that is a general problem with algorithms that need to “guess”.)

*Many PDFs one can get from the internet do not contain metadata for a table of content. But most of them contain at least an OCR layer. In such cases, one can mark the chapter and section headings on the screen: KOReader generates bookmarks for them which contain the text of the headings, and the bookmarks menu serves as an acceptable table of contents. (This is an incredibly helpful feature!)

KOReader is under a very active development: Currently there are monthly updates.
A: Update:
http://www.technologyreview.com/blog/mimssbits/27622/?ref=rss
It seems we finally got something having color....
A: I use a Hanlin V5. 
(Hanlin V5 is the Chinese name, but it is sold under many names,
such as Astak, BeBook,...)
It can read DJVU, PDF,... The 5"-screen is sometimes a bit too small for some of the texts, and the machine is sometimes a bit slow, but it works.
The storage is short, but it can be enlarged easily via the SD-card slot.
A: I suppose the OP wanted something with "electronic ink" because it's easy on the eyes. But since the time of posting technology has advanced and some and some new techniques are now available. 
I am currently using a Windows 10 laptop/tablet with a 12" OLED screen. OLED screens have the advantage that black=no light, unlike the older plasma screens. 
On my device I  changed the settings in Adobe, so that my documents are displayed with black background and gray letters (white letters are actually to bright). I added a screenshot for illustration. I set the brightness of my screen to around 40%. This can  easily be qualified as "easy on the eyes". I once red of my tablet for about 3 hours in a dark room and my eyes were not fatiqued (beyond what is reasonable for a 3 hour reading session). 
Another benefit is that you are using a regular laptop/tablet, so large files are no problem and maths will be displayed properly. 
As an extra, writing mathematics in a low lit room is now also doable, using appropriate settings of Windows (and a custom syntax-patterns.txt if you're using TeXworks. Picture added.) Also with minimal stress on the eyes.


