References References

Carry your BibTeX libraries with you on your iPad and iPhone!

A BibTeX library is a collection of bibliographic references (papers, books, reports, etc.), designed to work with the LaTeX typesetting system. Each library is stored in a specially-formatted text file (typically ending in .bib), which you can create with your favourite text editor.

The References app gives you an easy way to browse through and interact with your BibTeX libraries. You can scroll, search, follow links, and view file attachments. In particular:

– The app creates links from DOIs, MathSciNet references, ACM IDs, and of course URLs.
– The app understands elementary LaTeX, so if your titles and/or abstracts contain markup or mathematics (and if your LaTeX is simple enough) then the app can display them nicely.
– If you used BibDesk or JabRef to create your library, the app can view your file attachments (e.g., PDFs that you have attached to your references).
– The app supports BibLaTeX libraries as well as classic BibTeX.

The References app can open BibTeX libraries from anywhere on your device. In particular, you can use iCloud Drive to keep them synchronised between your devices.


To view file attachments (e.g., PDFs), the path to each file should be included in the corresponding entry in your BibTeX library. You can do this using the specially encoded Bdsk-File-* fields (as used by BibDesk), or the plain text File field (as used by JabRef). If you are writing your BibTeX files by hand, just add a File field giving the location of the attachment, such as File = {../PDFs/foo.pdf}.

All paths are relative to the location of your BibTeX library (so if your BibTeX library is Documents/BibTeX/papers.bib and you encode an attachment as ../PDFs/foo.pdf, then the app will look for the file Documents/PDFs/foo.pdf). On iOS 13, if your attachments are stored somewhere different, then you can just add their location as a new linked folder in the app, and the References app will still be able to find them.

There are some limitations to viewing file attachments:

– On iOS 12, you can only view attachments that are stored inside the References app. On iOS 13, you can view attachments from anywhere on your device (including iCloud Drive).
– You might have difficulties viewing attachments that are stored using a third-party file provider (e.g., DropBox). If you have problems, please mail the References developer with the details; in the meantime, you should be able to use iCloud Drive without trouble.


To learn more about BibTeX, see .…/id1481843213

Resolved an issue where .bib files are grayed out and cannot be selected, because another app already “owns” them.

Price: $1.99 USD
Version: 1.5
Size: 14.93 MB
Seller: Benjamin Burton
Released: 2019-11-08 00:21:47
Updated: 2019-12-19 02:12:12

Talk Timer Talk Timer

Discreetly tracks time while you give a talk / seminar / lecture, with taps on the wrist to remind you when your time is almost up.

This app runs entirely on Apple Watch. You do not need your phone.

You create a talk with three time limits — the stopping time, and two early warnings. Once you start a talk, the timer will count up from 0:00 on your watch. Each time you pass one of your three time limits, the watch will discreetly tap you on the wrist as a reminder. After the final stopping time, the timer will also turn red.

You can store as many different talks as you like (for instance, a 50 minute seminar talk, a 20 minute conference talk, and a 5 minute public debate). To edit the times for a talk, open the talk and press firmly on the screen.

The app includes watch face complications, which show the running time on the main watch face once you have started your talk.

It is recommended that you put your watch in silent mode during your talk. Otherwise the alerts will include small sounds along with the taps on the wrist.…/id1451270409

– With watchOS 6, Talk Timer can now run as an independent watch-only app.
– Sort your talks in different ways by pressing firmly on the list.
– Other updates for watchOS 6 and iOS 13.

Price: $0.99 USD
Version: 1.2
Size: 1.78 MB
Seller: Benjamin Burton
Released: 2019-02-03 09:08:36
Updated: 2019-09-25 22:52:32

PDF Projector PDF Projector

Projects PDF slideshows onto an external screen. If you have an Apple Watch, you can also use it as a remote control.

This app is useful if you write presentations using LaTeX Beamer, or LibreOffice Impress, or some other application that exports to PDF.

Simply open your PDF in the app and connect an external display (e.g., via VGA, HDMI, or AirPlay). Your slides will be displayed full-screen on the external display, while the app provides additional navigation controls on your iPad or iPhone.

You can navigate on your iPad or iPhone by tapping and swiping, or using the buttons on the toolbar, or scrolling through the thumbnails, or using an external keyboard. When in landscape mode, you will also see a preview of the next page (which you can turn on/off using the button on the upper toolbar).

You can browse and open any of your iCloud documents, or you can share PDFs from your favourite app to open in PDF Projector.


If you have an Apple Watch, you can use this as a remote control. Simply open a PDF document in the iPhone app and connect it to an external display, and then start the Watch app to use the remote control.

If you like to give long talks, you might want to configure your Watch to always show the last app when raising the screen (go to Settings / General / Wake Screen). This means that, even after a lot of talking, you will still see the remote control as soon as you raise your wrist.…/id1444555016

Now supports dark mode! Plus other updates for iOS 13.

Price: $0.99 USD
Version: 1.5
Size: 1.71 MB
Seller: Benjamin Burton
Released: 2018-11-28 08:27:58
Updated: 2019-09-25 17:59:07

Regina for 3-Manifolds Regina for 3-Manifolds

This app is for research mathematicians in 3-manifold and 4-manifold topology.

Have you encountered 3-manifolds and normal surfaces, or heard about the desktop software packages Regina or SnapPy? If so, then you might find this app useful. If not, but if you are curious as to what it’s all about, you might like to read about the Poincaré conjecture (é-conjecture), or hunt down a copy of Jeffrey Weeks’ excellent book “The Shape of Space”.

Regina is a software package for 3-manifold and 4-manifold topologists, with a focus on triangulations, normal surfaces, and angle structures. For 3-manifolds, it includes high-level tasks such as 3-sphere recognition, connected sum decomposition and Hakenness testing, comes with a rich database of census manifolds, and incorporates the SnapPea kernel for working with hyperbolic manifolds. For 4-manifolds, Regina offers several combinatorial and algebraic tools, as well as support for normal hypersurfaces. Advanced users can also access Regina’s mathematical engine using Python scripting.

This iPad app offers most of Regina’s functionality, but not all. For example, the iPad version does not support some of the more exotic import/export formats, and some mathematical functions are only accessible through Python (such as isomorphism testing, or manifolds of dimension ≥ 5). If you need these features then please download a desktop version of Regina from

If you have any questions, requests or feedback then please contact Ben or the Regina development team – see for details.…/id925244528

Regina for iPad now supports Python! Press the [>_] button in the top-right corner for direct access to Regina’s mathematical engine.

This release is a major overhaul for Python users:

– All of the code that was deprecated in version 5.0 has now been removed entirely. See for instructions on how to update your scripts.

– Many class names have changed, but most of these changes follow a standard pattern (classes of the form NFoo become Foo). The old class names have been kept, and will not be removed until Regina 6.0. See for details.

– More of Regina’s triangulation code is now generic, which means you can do more with higher-dimensional triangulations (e.g., triangulate boundary components, or compute homology).

This release also includes minor enhancements to the mathematics and the user interface (e.g., syntax highlighting for script packets, and the ability to cancel long Turaev-Viro calculations).

Price: Free
Version: 5.1
Size: 82.97 MB
Seller: Benjamin Burton
Released: 2014-11-03 02:20:12
Updated: 2016-12-21 00:46:15

Modular Arithmetic Modular Arithmetic

A calculator for arithmetic modulo N. It lets you choose a fixed modulus, and then make lots of calculations without having to press a “mod” button again and again. It also:

– follows the order convention;
– supports arbitrarily large numbers;
– performs fast modular division and exponentiation;
– can show a full transcript of your calculation.

Modular arithmetic is a “calculus of remainders”. It features throughout mathematics and computer science, and has applications from cryptography to barcodes to music.

The basic idea is that you choose a modulus N, and then reduce every number to one of the integers 0,1,2,…,N−1 according to what remainder it leaves when dividing by N.

For example, using a modulus of 17:

40 ≡ 6 (since 40 ÷ 17 leaves a remainder of 6);
17 ≡ 0 (since 17 ÷ 17 leaves no remainder at all).

Arithmetic follows these same rules. Still using a modulus of 17:

15 + 7 ≡ 5 (since 22 ≡ 5);
3 × 9 ≡ 10 (since 27 ≡ 10);
5 ^ 3 ≡ 6 (since 125 ≡ 6).

Subtraction and division behave in a way that complements addition and multiplication:

−1 ≡ 16 (since 16 + 1 = 17 ≡ 0);
1/2 ≡ 9 (since 9 × 2 = 18 ≡ 1);
4 – 7 ≡ 14 (since 14 + 7 = 21 ≡ 4);
7 ÷ 3 = 8 (since 8 × 3 = 24 ≡ 7).

There are no negative numbers or fractions: like −1 and 7 ÷ 3 in the examples above, these are also reduced to one of 0,1,…,N−1.

As usual, you cannot divide by zero. You also cannot divide if the right hand side has any common factors with the modulus. If we change our modulus to 10, then the following operations all generate errors:

3 ÷ 20 (since 20 ≡ 0);
7 ÷ 8 (since 8 and 10 have a common factor of 2).

Integers can be arbitrarily large. For instance, if we set our modulus to 2305843009213693951 (a Mersenne prime), then:

5 ^ 2305843009213693950 ≡ 1 (by Fermat’s little theorem).

The code is written carefully, and is backed up by a thorough suite of 186 automated tests.

This app supports external keyboards, Siri Shortcuts, and (on iPad) Slide Over and Split View.…/id687735575

Now supports dark mode in iOS 13.

Price: $1.99 USD
Version: 3.5
Size: 1.46 MB
Seller: Benjamin Burton
Released: 2013-08-17 19:43:40
Updated: 2019-09-25 21:59:20