Editing Summer of Code - Getting Started

{{Note|GNU Octave [https://summerofcode.withgoogle.com/organizations/5849336744771584/ has been selected] as mentoring organization for GSoC 2021.}}

Since 2011 the GNU Octave project has mentored 38 students in [[Summer of Code]] (SoC) programs by [https://summerofcode.withgoogle.com/ Google] and [https://socis.esa.int/ ESA].  Those programs aim to advertise open-source software development and to attract potential new Octave developers.

= Steps toward a successful application =

# 😉💬 '''We want to get to know you (before the deadline).  Communicate with us.'''
#* Join [https://octave.discourse.group/ '''Octave Discourse'''] or [[IRC]]. Using a nickname is fine.
#* Show us that you're motivated to work on Octave 💻.  There is no need to present an overwhelming CV 🏆; evidence of involvement with Octave is more important.
#* '''<span style="color:darkblue;">If you never talked to us, we will likely reject your proposal</span>''', even it looks good 🚮
# 👩‍🔬 '''Get your hands dirty.'''
#* We are curious about your programming skills 🚀
#** Your application will be much stronger if you [https://savannah.gnu.org/bugs/?group=octave fix Octave bugs] or [https://savannah.gnu.org/patch/?group=octave submit patches] before or during the application period.
#** You can take a look at the [[short projects]] for some simple bugs to start with.
#* '''Use Octave!'''
#** If you come across something that does not work the way you like ➡️ try to fix that 🔧
#** Or if you find a missing function ➡️ try to implement it.
# 📝💡 '''Tell us what you are going to do.'''
#* Do not write just to say what project you're interested in.  Be specific about what you are going to do, include links 🔗, show us you know what you are talking about 💡, and ask many [http://www.catb.org/esr/faqs/smart-questions.html smart questions] 🤓
#* Remember, '''we are volunteer developers and not your boss''' 🙂
# 📔 '''Prepare your proposal with us.'''
#* If we see your proposal for the first time after the application deadline, it might easily contain some paragraphs not fully clear to us.  Ongoing interaction will give us more confidence that you are capable of working on your project 😓
#* Try to show us as early as possible a draft of your proposal 👍
#* Then submit the proposal following the applicable rules, e.g. for [https://google.github.io/gsocguides/student/writing-a-proposal GSoC].

= How do we judge your application? =

Depending on the mentors and SoC program there are varieties, but typically the main factors considered would be:

* '''You have demonstrated interest in Octave and an ability to make substantial modifications to Octave'''
*: The most important thing is that you've contributed some interesting code samples to judge your skills. It's OK during the application period to ask for help on how to format these code samples, which normally are Mercurial patches.

* '''You showed understanding of your topic'''
*: Your proposal should make it clear that you're reasonably well versed in the subject area and won't need all summer just to read up on it.

* '''Well thought out, adequately detailed, realistic project plan'''
*: "I'm good at this, so trust me" isn't enough.  In your proposal, you should describe which algorithms you'll use and how you'll integrate with existing Octave code.  You should also prepare a project timeline and goals for the midterm and final evaluations.

= What you should know about Octave =

GNU Octave is mostly written in C++ and its own scripting language that is mostly compatible with Matlab. There are bits and pieces of Fortran, Perl, C, awk, and Unix shell scripts here and there. In addition to being familiar with C++ and Octave's scripting language, you as successful applicant will be familiar with or able to quickly learn about Octave's infrastructure. You can't spend the whole summer learning how to build Octave or prepare a changeset and still successfully complete your project 😇

You should know:
# How to build Octave from it's source code using [http://en.wikipedia.org/wiki/GNU_build_system the GNU build system].
#* Read in this wiki: [[Developer FAQ]], [[Building]]
#* Tools to know: [https://en.wikipedia.org/wiki/GNU_Compiler_Collection gcc], [https://en.wikipedia.org/wiki/Make_(software) make]
# How to submit patches (changesets).
#* Read in this wiki: [[Contribution guidelines]], [[Mercurial]]
#* Tools to know: [https://en.wikipedia.org/wiki/Mercurial Mercurial (hg)], [https://en.wikipedia.org/wiki/Git git]

= Suggested projects =

The following suggested projects are distilled from the [[Projects]] page for the benefit of potential SoC students.  You can also look at our [[Summer of Code|completed past projects]] for more inspiration.

{{Note|Do you use Octave at your university or do you have some numerical project in mind?  You are always welcome to '''propose your own projects'''.  If you are passionate about your project, it will be easy to find an Octave developer to mentor and guide you.}}

== ode15{i,s} : Matlab Compatible DAE solvers ==

An initial implementation of Matlab compatible Differential Algebraic Equations (DAE) solvers, {{manual|ode15i}} and {{manual|ode15s}}, based on [https://computing.llnl.gov/projects/sundials SUNDIALS], 
was done by [https://gsoc2016ode15s.blogspot.com/ Francesco Faccio during GSoC 2016].  The code is maintained in the main Octave repository and consists mainly of the following three files: [https://hg.savannah.gnu.org/hgweb/octave/file/tip/libinterp/dldfcn/__ode15__.cc {{path|libinterp/dldfcn/__ode15__.cc}}], [https://hg.savannah.gnu.org/hgweb/octave/file/tip/scripts/ode/ode15i.m {{path|scripts/ode/ode15i.m}}] and [https://hg.savannah.gnu.org/hgweb/octave/file/tip/scripts/ode/ode15s.m {{path|scripts/ode/ode15s.m}}].

The {{manual|decic}} function for selecting consistent initial conditions for ode15i can be made more Matlab compatible by using [https://faculty.smu.edu/shampine/cic.pdf another algorithm].  Another useful extension is to make ode15{i,s} work with datatypes other than double and to improve interpolation at intermediate time steps.

* '''Required skills'''
: Knowledge of Octave, C/C++; familiarity with numerical methods for DAEs
* '''Potential mentors'''
: Francesco Faccio, Carlo de Falco, Marco Caliari, Jacopo Corno, Sebastian Schöps

== Using Python within Octave ==

[[Pythonic]] allows one to call Python functions and interact with Python objects from within Octave .m file code and from the Octave command line interface.  Pythonic may eventually not be a separate package, but rather a core feature of Octave.  This project aims to improve Pythonic with the goal of making the package more stable, maintainable, and full-featured.

Based on a previous summer project related to Pythonic, this work will consist of fast-paced collaborative software development based on tackling the [https://gitlab.com/mtmiller/octave-pythonic/issues Pythonic issue list].  You would also be expected to participate in software design decisions and discussion, as well as improve documentation, doctests, and unit tests.  As an example of the sorts of decisions being made, note that Octave indexes from 1 whereas Python typically indexes from 0; in which cases is it appropriate to make this transparent to the user?

* '''Required skills'''
: Knowledge of Octave, C/C++, Python
* '''Potential mentors'''
: Mike Miller, Colin B. Macdonald, Abhinav Tripathi

== Improve TIFF image support ==

[https://en.wikipedia.org/wiki/TIFF Tag Image File Format (TIFF)] is the de facto standard for scientific images.  Octave uses the [http://www.graphicsmagick.org/ GraphicsMagic] (GM) C++ library to handle [http://www.graphicsmagick.org/formats.html TIFF and many others image formats]. However, GM still has several limitations:

* GM has build option {{codeline|quantum}} which defines the bitdepth to use when reading an image:
** Building GM with '''high quantum''' means that images of smaller bitdepth will take a lot more memory when reading.
** Building GM with '''low quantum''' will make it impossible to read images of higher bitdepth. It also means that the image needs to always be rescaled to the correct range.
* GM supports unsigned integers only, thus incorrectly reading files such as TIFF with floating-point data.
* GM hides details of the image such as whether the image file is indexed.  This makes it hard to access the real data stored on file.

This project aims to implement better TIFF image support using [https://en.wikipedia.org/wiki/Libtiff libtiff], while leaving GM handle all other image formats.  After writing a [https://octave.org/doc/v6.1.0/classdef-Classes.html classdef] interface to libtiff, improve the Octave functions {{manual|imread}}, {{manual|imwrite}}, and {{manual|imfinfo}} to make use of it.

* '''Required skills'''
: Knowledge of Octave, C/C++
* '''Potential mentors'''
: Carnë Draug

== PolarAxes and Plotting Improvements ==

Octave currently provides supports for polar axes by using a Cartesian 2-D axes and adding a significant number of properties and callback listeners to get things to work.  What is needed is the implementation of a dedicated "polaraxes" object in C++.  This will require creating a new fundamental graphics object type, and programming in C++/OpenGL to render the object.  When "polaraxes" exists as an object type, then m-files will be written to access them, including polaraxes.m, polarplot.m, rticks.m, rticklabels.m, thetaticks, thetaticklabels.m, rlim.m, thetalim.m.  This relates to bug {{bug|49804}}.

* '''Required skills'''
: Knowledge of Octave, C/C++; optional experience with OpenGL programming
* '''Potential mentors'''
: Rik 

== Table datatype ==

In 2013, Matlab introduced a [https://www.mathworks.com/help/matlab/tables.html new table datatype] to conveniently organize and access data in tabular form.  This datatype has not been introduced to Octave yet (see bug {{bug|44571}}).  However, there are two initial implementation approaches https://github.com/apjanke/octave-tablicious and https://github.com/gnu-octave/table.

Based upon the existing approaches, the goal of this project is to define an initial subset of [https://www.mathworks.com/help/matlab/tables.htmlMatlab's table functions], which involve sorting, splitting, merging, and file I/O and implement it within the given time frame.

* '''Required skills'''
: Knowledge of Octave, C/C++
* '''Potential mentors'''
: [[User:siko1056|Kai]]

== Adding functionality to packages ==

=== YAML encoding/decoding ===

[https://en.wikipedia.org/wiki/YAML YAML], is a very common human readable and structured data format.  Unfortunately, GNU Octave (and Matlab) still lacks of builtin support of that omnipresent data format.  Having YAML support, Octave can easily read and write config files, which often use YAML or JSON.  The latter JSON format has been [[Summer of Code#GSoC_2020 | successfully implemented for Octave during GSoC 2020]].

The goal of this project is to repeat the GSoC 2020 success story with [https://github.com/biojppm/rapidyaml Rapid YAML] or another fast C/C++ library.

The first step is research about existing Octave/Matlab and C/C++ implementations, for example:

* https://code.google.com/archive/p/yamlmatlab/ (uses Java)
* http://vision.is.tohoku.ac.jp/~kyamagu/ja/software/yaml/ (uses Java)

Then evaluate (and to cherry pick from) existing implementations above, compare strength and weaknesses.  After this, an Octave package containing en- and decoding functions (for example <code>yamlencode</code> and <code>yamldecode</code>) shall be created.  This involves proper documentation of the work and unit tests to ensure the correctness of the implementation.

Finally, the package is considered to be merged into core Octave, probably after the GSoC project.  However, it can be used immediatly from Octave as package and is backwards-compatible with older Octaver versions.

* '''Required skills'''
: Knowledge of Octave and C/C++
* '''Potential mentors'''
: [[User:siko1056|Kai]]


=== OCS package ===

The [[Ocs package | OCS package]] is a circuit simulator. The objective of this project is to increase compatibility with [https://en.wikipedia.org/wiki/SPICE SPICE] and improve compatibility with other Octave packages, e.g. the [[Control package]].  Please study the [https://octave.sourceforge.io/ocs/overview.html available functions] of this package. 

* '''Required skills'''
: Knowledge of Octave, C/C++; FORTRAN API knowledge
* '''Potential mentors'''
: Sebastian Schöps, Carlo de Falco

=== Symbolic package ===

The [[Symbolic package]] provides symbolic computing and other [https://en.wikipedia.org/wiki/Computer_algebra_system computer algebra system] tools.  The main component of Symbolic is a pure m-file class "@sym" which uses the Python package [https://www.sympy.org SymPy] to do (most of) the actual computations.  The package aims to expose the full functionality of SymPy while also providing a high level of compatibility with the Matlab Symbolic Math Toolbox.  The Symbolic package requires communication between Octave and Python.  In 2016 another GSoC project successfully re-implemented this communication using the new [[Pythonic|Pythonic package]].

This project proposes to go further: instead of using Pythonic only for the communication layer, we'll use it throughout the Symbolic project.  For example, we might make "@sym" a subclass of "@pyobject".  We also could stop using the "python_cmd" interface and use Pythonic directly from methods.  The main goal was already mentioned: to expose the ''full functionality'' of SymPy.  For example, we would allow OO-style method calls such as <code>f.diff(x)</code> instead of <code>diff(f, x)</code>.

* '''Required skills'''
: Knowledge of Octave, C/C++, Python; object-oriented programming (OOP) in Octave
* '''Potential mentors'''
: Colin B. Macdonald, Mike Miller, Abhinav Tripathi

=== TISEAN package ===

The [[TISEAN package]] provides an Octave interface to [https://www.pks.mpg.de/~tisean/Tisean_3.0.1/index.html TISEAN] is a suite of code for nonlinear time series analysis.  In 2015, another GSoC project started with the work to create interfaces to many TISEAN functions, but [[TISEAN_package:Procedure | there is still work left to do]].  There are missing functions to do computations on spike trains, to simulate autoregresive models, to create specialized plots, etc.  Which are of importance for many scientific disciplines involving statistical computations and signal processing.
 
* '''Required skills'''
: Knowledge of Octave, C/C++; FORTRAN API knowledge
* '''Potential mentors'''
: [[User:KaKiLa|KaKiLa]]

[[Category:Summer of Code]]
[[Category:Project Ideas]]