Sage Days 96

Sage days 96 to be held at the Fields Institute for the program Teichmüller Theory and its Connections to Geometry, Topology and Dynamics. The schedule is available on the Fields website. This wiki page will be updated with all documents relative to the workshop (worksheets, tutorials, demos, nice pictures, etc).

In order to assist to the workshop you are asked to come with your laptop (though you are also welcome without laptop). It would also be great if you could make sure that Sage is installed on it (see "Sage Installation" below).

Worksheets

• Introduction with the picture S_2_1.svg to be downloaded in the same folder (the worksheet is also available as intro.en.rst and intro.en.pdf)

• Programming

  • Chapter 1: First steps

  • Chapter 2: List and for loops

  • Chapter 3: Conditionals if/elif/else

  • Chapter 4: Functions

  • Chapter 5: While loops

  • Chapter 6: Advanced exercises

• Thematic tutorials

  • Floating point and stability

  • Simple random walk on Z

  • Collatz conjecture

  • Python dictionaries and graph theory (you also need to download the images euler.png and graph0.png)

  • The Burrows-Wheeler transform

• flipper tutorial (for the last exercises you will need flipper_nf_conversion.py)

• flatsurf and surface_dynamics demo.

Sage Installation

The installation procedure depends on your operating system:

• Debian (versions >= 9.0) and Ubuntu (versions >= 18.04): install the packages sagemath, sagemath-doc-en and sagemath-jupyter

• archlinux: install the packages sagemath, sagemath-doc and sagemath-jupyter

• gentoo: you can give a try to sage on gentoo

• all other systems (GNU/Linux, OSX, Windows): go to the main SageMath website, go to the download section, choose a download server close to your location and download the Sage binary that corresponds to your operating system.

• If you run GNU/Linux or OSX you can also try to compile the software from sources. The procedure is described in the documentation.

Installing flipper, snappy, flatsurf and surface_dynamics

We will be interested in these Sage days to four Python-Sage modules that provide many tools to work with surfaces and 3-dimensional manifolds

• flipper: mapping classes (homeomorphisms of surfaces)

• flatsurf: translation surfaces (affine transformation, linear flow, etc)

• surface_dynamics: interval exchange transformations, origamis and more

• snappy: 3-d hyperbolic geometry

These packages are installed through pip. Depending how you did install Sage you might run in different kind of complications.

Generic Installation

This installation would work in most situations. Though if you happen to be in one of the specific situations listed below, just jump to that section.

• To install flipper, it should work out of the box with the following command (if you do not know how to open a command line, ask one of the organizer)

  •    $ sage -pip install flipper --user

    If the above command does not work, ask for help. If it does work, go to next step.
• To install surface_dynamics and snappy you need a working version of gcc and g++ (that should be the case for most of you). The commands are similar to the one before

  •    $ sage -pip install surface_dynamics --user
       $ sage -pip install snappy --user

    Similarly, report any error or weird behavior.

• Lastly, to install flatsurf, look at the instructions at https://github.com/videlec/sage-flatsurf

Mac OS X specifics

If you are using the binaries for Mac OS X, the computer might complain with could not fetch URL .... In that situation, you can try the two following solutions

1. You do have Xcode installed with the command line tools. In this case you can recompile the Python shipped with Sage with SSL support with

    $ sage -i openssl
    $ sage -f python2 

   Then go back to the instructions "Installing flipper, snappy, flatsurf and surface_dynamics".
2. The alternative to option 1 is to download each package independently:

   • flipper-0.12.3.tar.gz

   • surface_dynamics-0.4.0.tar.gz

   • snappy-2.6.tar.gz

   • master.zip

   and then install them via

    $ sage -pip install flipper-0.12.3.tar.gz
    $ sage -pip install surface_dynamics-0.4.0.tar.gz
    $ sage -pip install snappy-2.6.tar.gz
    $ sage -pip master.zip

Ubuntu 16.04 with ppa

If you run Ubuntu 16.04 and you install Sage with the ppa then do

$ sage -sh
(sage-sh)$ pip install flipper --user
(sage-sh)$ pip install surface_dynamics --user
(sage-sh)$ pip install snappy --user
(sage-sh)$ exit

(The sage -sh command brings you to a special environment where you have access to Sage Python)

Ubuntu >= 18.04 and Debian >= 8.0 packages

If you happen to have installed the packages sagemath and sagemath-jupyter from your package manager in Debian/Ubuntu then you would need to do

$ source /usr/share/sagemath/bin/sage-env
$ pip install flipper --user
$ pip install surface_dynamics --user
$ pip install snappy --user

For the installation of flatsurf, follows the instruction at https://github.com/videlec/sage-flatsurf and replace any instance of sage -pip by pip.

Archlinux

Do

$ sage -sh
(sage-sh)$ pip2 install flipper --user
(sage-sh)$ pip2 install surface_dynamics --user
(sage-sh)$ pip2 install snappy --user
(sage-sh)$ exit
$

For the installation of flatsurf, follows the instruction at https://github.com/videlec/sage-flatsurf and replace any instance of sage -pip by pip.

Windows

Before following the generic instruction do

(sage-sh) $ apt-cyg install libcrypt-devel
(sage-sh) $ apt-cyg install liblapack-devel

Organizers and participants

See the Fields Institute webpage.

Link to Pad

At this pad, we will coordinate lunch and so on.