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Summer of Code - Getting Started
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Revision as of 19:54, 29 March 2020

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~~ ~~
~~=== Make specfuns special again ===~~
~~ ~~
~~Traditionally, problem solving environments like Octave provide simple interfaces to numerical linear algebra, special function evaluation, root finding, and other tools. Special functions (such as Bessel functions, exponential integrals, LambertW, etc) are expected by users to "just work". But many of Octave's special functions could be improved to improve their numerical accuracy. Generally a user might expect these to be accurate to full 15 digits. Software testing is important to Octave; this project would improve the tests of many special functions, in particular by comparing the output with slow-but-accurate symbolic computations.~~
~~ ~~
~~State: some bugs include [https://savannah.gnu.org/bugs/?48307 #48307] (sinc), [https://savannah.gnu.org/bugs/?47738 #47738] (expint), [https://savannah.gnu.org/bugs/?47800 #47800] (gammainc), [https://savannah.gnu.org/bugs/?48036 #48036] (gammaincinv) [https://savannah.gnu.org/bugs/index.php?48316 #48316] (besselj) ''TODO: add others?'' The unmaintained specfun pkg had some poor implementations (e.g., divergence for large x, see [https://github.com/cbm755/octsympy/issues/416].). See also the Symbolic functions in `@double`: these probably should have native double implementations.~~
~~ ~~
~~* '''Required skills'''~~
~~: Octave m-file programming, some familiarity with Approximation Theory (a branch of mathematics).~~
~~* '''Difficulty'''~~
~~: Medium (mathematics needed, but on the other hand, perhaps little or no C++).~~
~~* '''Potential mentors'''~~
~~: Marco Caliari, Colin Macdonald, others?~~
~~ ~~
~~How to get started: pick a special function, see if it has tests: contribute a patch that adds more tests, e.g., comparing its values to symbolic computations or other highly accurate solutions~~
~~ ~~
~~ ~~
~~How to get started: learn about Chebfun, browse Octave's bug list for classdef-related bugs.~~
~~ ~~
~~First steps: clone this Chebfun [https://github.com/cbm755/chebfun/tree/octave_dev octave_dev branch]. On that, "f = chebfun(@(x) sin(x), [-2 6])" should work with Octave 4.3.0+ and maybe even with 4.2.1. Check that "f(pi)" and "g = f + 1" work. A good first task would be to study [https://github.com/cbm755/chebfun/commit/e20b0ad2dc89cfe8e50ba461b864eff7d5bbef17 this commit], a workaround for "f.funs{1}" using "temp = f.funs; temp{1}". "2*f" is failing, can you fix it, perhaps with this workaround? Or can you make "f.funs{1}" work by changing something in "@chebfun/subsref.m"?~~
~~ ~~
~~=== Interval package ===~~
~~ ~~
~~The [[Interval_package|interval package]] provides several arithmetic functions with accurate and guaranteed error bounds. Its development started in the end of 2014 and there is some fundamental functionality left to be implemented. See the [https://octave.sourceforge.io/interval/overview.html list of functions], basically any missing numeric Octave function could be implemented as an interval extension in the package. Potential projects:~~
~~* Implement missing algorithms (as m-files)-difficulty and whether knowledge in interval analysis is required depends on the particular function. Of course, you may use papers which present such algorithms.~~
~~* Improve existing algorithms (support more options for plotting, support more options for optimizers, increase accuracy, …)~~
~~* Integrate functions from VERSOFT [http://uivtx.cs.cas.cz/~rohn/matlab/] in the package (some work has already been done and current progress is tracked in [[Interval_package#VERSOFT]]). This basically involves conversion of the documentation into Texinfo format, use [[Contribution_guidelines#Coding_style|Octave coding guidelines]] and to make sure that any called functions are available in the interval package. VERSOFT is originally based on INTLAB [http://www.ti3.tu-harburg.de/rump/intlab/], a proprietary Octave/Matlab package. Some functions may be missing. Also, the interval package doesn't support complex numbers, so it might not be possible to migrate some functions.~~
~~* List more interesting use cases of interval arithmetic in the package's manual [https://octave.sourceforge.io/interval/package_doc/Examples.html]~~
~~ ~~
~~* '''Required skills'''~~
~~: m-file scripting, basic knowledge of computer arithmetics (especially floating-point computations), interval analysis (depending on the functions to implement).~~
~~* '''Difficulty'''~~
~~: Medium.~~
~~* '''Mentor and co-mentor'''~~
~~: [[User:oheim|Oliver Heimlich]], [[User:Siko1056|Kai T. Ohlhus]]~~
~~* install from URLs~~
~~To do this enhacenment effectively, a refactoring of the current {{codeline|pkg}} code will be needed.~~~~[https://bitbucket.org/carandraug/octave/commits/branch/pkg This job was started once], but due to diverging and growing specifications, it stalled. ~~~~In this project we will focus on the most needed features, keeping the requirements to a minimum. ~~ Many of these problems have been solved in other languages. Familiarity with how other languages handle this problem will be useful to come up with elegant solutions. In some cases, there are standards to follow. For example, there are specifications published by freedesktop.org about where files should go ([http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html base directory spec]) and Windows seems to have its own standards. See bugs {{bug|36477}} and {{bug|40444}} for more details.
~~ ~~
~~=== Command line suggestion feature ===~~
~~ ~~
~~Currently Octave has no mechanism for suggesting corrections to typographic errors on the command line. An autocomplete/suggestion function is provided (using the double-TAB shortcut), but recent discussions have indicated a desire for a more proactive measure to catch user error. Potential applicants are referred to bug {{bug|46881}} regarding the usage of grey vs. gray. ~~
~~ ~~
~~Suggested improvements are:~~
~~* provide one or more suggested corrections to the user when a command line entry produces an error.~~
~~* recognition and suggested correction for apparent syntax errors~~
~~* function suggestion(s) when a 'close' match is found (close remains to be defined)~~
~~* multiple suggestions if more than one option seems likely, along with a user-friendly method of selecting the appropriate choice.~~
~~* user selectable option to disable and/or customize the suggestion behavior~~
~~* correct operation, or graceful degradation, whether Octave is run in GUI or command-line mode. ~~
~~ ~~
~~As mentioned in the bug {{bug|46881}} discussion, this project has little-to-no relation to m-code compatibility. As such, emulation of the behavior of other software is not required, nor even necessarily desired. Octave is free to implement as simple or complex a solution to this feature request as is necessary to provide the best experience to the user. There may be tools, features, or code from other license-compatible projects that can be of use here, and the applicant would be encouraged to identify and leverage such resources as appropriate. ~~
~~ ~~
~~* '''Minimum requirements'''~~
~~: TBD~~
~~* '''Difficulty'''~~
~~: Easy to Medium.~~
~~* '''Mentor'''~~
~~: Undetermined~~
~~ ~~
~~=== SPQR Interface ===~~
~~ ~~
~~Octave implements QR factorization for sparse matrices, but it does so with an older library. This has caused fundamental issues, including segfaults as recorded here (https://savannah.gnu.org/bugs/?func=detailitem&item_id=51950). The goal of this project is to program an interface to the API for the SQPR library (http://faculty.cse.tamu.edu/davis/suitesparse.html). This is the same library that Matlab uses for this purpose.~~
~~ ~~
~~* '''Minimum requirements'''~~
~~: Ability to read and write C++ code.~~
~~* '''Difficulty'''~~
~~: Medium.~~
~~* '''Mentor'''~~
~~: ~~
~~ ~~
~~== GUI ==~~
~~ ~~
~~=== GUI Variable Editor and Property Inspector ===~~
~~ ~~
~~Octave has a preliminary implementation of a Variable Editor: a spreadsheet-like tool for quickly editing and visualizing variables. The initial phase of the project will be learning how the implementation was done.~~
~~ ~~
~~With the knowledge gained, the second part of the project will be to implement a Property Inspector. This is a spreadsheet like interface to the many, many graphics properties that exist and are different on a per-object basis. The goal would be not only the concise-display of the existing properties, but a reasonable user interface to change them. As examples, boolean properties should be able to be toggled with a double-click; Radio properties should have a drop-down list of only the supported options; Other properties that can be modified should have the constraints built-in (for example, Linewidth must be a scalar, while Position must be a 1x4 vector). It would also be important to have easy access to the documentation of a property.~~
~~ ~~
~~For reference, Matlab has a similar Property Inspector (https://www.mathworks.com/help/matlab/ref/inspect.html).~~
~~ ~~
~~* '''Minimum requirements'''~~
~~: Ability to read and write C++ code. Experience with Qt toolkit and GUI programming is optional, but desirable.~~
~~* '''Difficulty'''~~
~~: Medium.~~
~~* '''Mentor'''~~
~~:~~

→OCS: Add link to open bugs on Savannah.

The following is distilled from the [[Projects]] page for the benefit of potential [https://summerofcode.withgoogle.com Google] and [~~http~~https://~~sophia.estec~~socis.esa.int/~~socis ~~ESA] Summer of Code (SoC) students. Although students are welcome to attempt any of the projects in that page or any of their own choosing, here we offer some suggestions on what good student projects might be.

You can also take a look at last years [[Summer of Code]] projects for inspiration.

== Help Us Get To Know You ==

*~~: ~~If you aren't communicating with us before the application is due, your application will not be accepted.

*:* '''Join the [https://lists.gnu.org/mailman/listinfo/octave-maintainers maintainers mailing list]''' or read the archives and see what topics we discuss and how the developers interact with each other.

*:* '''Hang out in our [https://webchat.freenode.net/?channels=#octave IRC channel]'''. Ask questions, answer questions from users, show us that you are motivated, and well-prepared. There will be more applicants than we can effectively mentor, so do ask for feedback on your public application to increase the strength of your proposal!

*: You should be doing something that interests you, and should not need us to tell you what to do. Similarly, you shouldn't ask us what to do either.

*:* When you email the list and mentors, do not write it to say in what project you're interested. Be specific about your questions and clear on the email subject. For example, do not write an email with the subject "GSoC student interested in the ND images projects". Such email is likely be ignored. Instead, show you are already working on the topic, and email "Problem implementing morphological operators with bitpacked ND images".

*:* It is good to ask advice on how to solve something you can't but you must show some work done. Remember, we are mentors and not your boss. Read [http://www.catb.org/esr/faqs/smart-questions.html How to ask questions the smart way]~~:~~~~*:*~~: <blockquote ~~cite="http://www.catb.org/esr/faqs/smart-questions.html"~~>''Prepare your question. Think it through. Hasty-sounding questions get hasty answers, or none at all. The more you do to demonstrate that having put thought and effort into solving your problem before seeking help, the more likely you are to actually get help.''</blockquote>

*:* It can be difficult at the beginning to think on something to do. This is nature of free and open source software development. You will need to break the mental barrier that prevents you from thinking on what can be done. Once you do that, you will have no lack of ideas for what to do next.

*:* Use Octave. Eventually you will come across something that does not work the way you like. Fix that. Or you will come across a missing function. Implement it. It may be a hard problem (they usually are). While solving that problem, you may find other missing capabilities or smaller bug fixes. Implement and contribute those to Octave.

== Find Something That Interests You ==

*: It's '''critical''' that you '''find a project that excites you'''. You'll be spending most of the summer working on it (we expect you to treat the SoC as a full-time job).

*: Don't just tell us how interested you are, show us that you're willing and able to '''contribute''' to Octave. You can do that by [https://savannah.gnu.org/bugs/?group=octave fixing a few bugs] or [~~http~~https://savannah.gnu.org/patch/?group=octave submitting patches] well before the deadline, in addition to regularly interacting with Octave maintainers and users on the mailing list and IRC. Our experience shows us that successful SoC students demonstrate their interest early and often.

== Prepare Your Proposal With Us ==

*: By working with us to prepare your proposal, you'll be getting to know us and showing us how you approach problems. The best place for this is your Wiki user page and the [https://webchat.freenode.net/?channels=#octave IRC channel].

*: [http://en.wikipedia.org/wiki/GNU_build_system The GNU build system] is used to build Octave.

*: While you generally don't need to understand too much unless you actually want to change how Octave is built, you should be able to understand enough to get a general idea of how to build Octave.

*: If you've ever done a {{Codeline|./configure && make && make install}} series of commands, you have already used the GNU build system.

*: '''You must demonstrate that you are able to build the development version of Octave from sources before the application deadline.''' Linux is arguably the easiest system to work on. Instructions:

*:* [[Building]]

*:* [https://~~www.gnu~~octave.org~~/software/octave~~/doc/interpreter/Installation.html Octave Manual on Installing Octave]

* '''The Version Control System'''

*: We use [https://www.mercurial-scm.org/ Mercurial] (abbreviated hg).

* '''The Procedure for Contributing Changesets'''

*: You will be expected to follow the same procedures as other contributors and core developers.

*: You will be helping current and future Octave developers by using our standard style for changes, commit messages, and so on. You should also read the same [[Contribution guidelines | contribution]] [~~http~~https://hg.savannah.gnu.org/hgweb/octave/file/tip/etc/HACKING.md guidelines] we have for everyone.

*: [[Hg_instructions_for_mentors#Mercurial_Tips_for_SoC_students | This page]] describes the procedures students are expected to use to publicly display their progress in a public mercurial repo during their work.

* '''The Maintainers Mailing List'''

*: Unless your primary mentor has a strong preference for some other method of communication, the IRC channel will likely be your primary means of communicating with your mentor and Octave developers.

* '''The Octave Forge Project'''

*: [https://octave.sourceforge.io/ Octave~~-~~Forge] is a collection of contributed packages that enhance the capabilities of core Octave. They are somewhat analogous to Matlab's toolboxes.

* '''Related Skills'''

*: In addition, you probably should know '''some''' mathematics, engineering, experimental science, or something of the sort.

= Suggested projects =

The following projects are broadly grouped by category and probable skills required to tackle each. Remember to check [[Projects]] for more ideas if none of these suit you, and your own ideas are always welcome. You can also look at our [[Summer of Code|completed past projects]] for more inspiration.

{{Note|~~these ~~These are suggested projects but you are welcome to propose your own projects provided you find an Octave mentor}}

== Summary table ==

! <br />!! !! !! !! !! !!

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~Make_specfuns_special_again ~~ode15.7Bi.2Cs.7D_:_Matlab_Compatible_DAE_solvers | ~~Make specfuns special again~~ode15{i,s} : Matlab Compatible DAE solvers]] || Carlo de Falco || Francesco Faccio, Marco Caliari ~~|| Colin Macdonald~~, ~~Ankit Raj ~~Jacopo Corno, Sebastian Schöps || Numerical || No || Medium || ~~[https://gsocspecfun.blogspot.de/ ~~GSoC ~~2017]~~2016

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~ode15s_:_Matlab_Compatible_DAE_solver ~~Improve_logm.2C_sqrtm.2C_funm | ~~ode15{i~~Improve logm, sqrtm,~~s} : Matlab Compatible DAE solvers~~funm]] || ~~Carlo de Falco ~~? || ~~Francesco Faccio, ~~Marco Caliari, ~~Jacopo Corno, Sebastian Schöps ~~Mudit Sharma || Numerical || [https://github.com/RickOne16/matrix No ] || ~~Medium ~~Hard || ~~GSoC ~~Independent devs 2016

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~Improve_logm.2C_sqrtm.2C_funm ~~Improve_iterative_methods_for_sparse_linear_systems | Improve ~~logm, sqrtm, funm~~iterative methods for sparse linear systems]] || ~~Jordi Gutiérrez Hermoso ~~Marco Caliari || ~~Marco Caliari, Mudit Sharma ~~Carlo de Falco || Numerical || ~~[https://github.com/RickOne16/matrix ~~No~~] ~~ || Hard || ~~Independent devs ~~SOCIS 2016

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~Improve_iterative_methods_for_sparse_linear_systems ~~EPA_hydrology_software_suite | ~~Improve iterative methods for sparse linear systems~~EPA hydrology software suite]] || ~~Marco Caliari ~~[[User:KaKiLa| KaKiLa]] || ~~Carlo de Falco ~~? || ~~Numerical ~~Octave Forge || ~~No ~~Yes || ~~Hard ~~Medium || ~~SOCIS 2016~~Never

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~EPA_hydrology_software_suite ~~FullSWOF overland flow simulator | ~~EPA hydrology software suite~~FullSWOF overland flow simulator]] || [[User:KaKiLa| KaKiLa]] || ? || Octave Forge || Yes || Medium || Never

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~FullSWOF overland flow simulator ~~TISEAN_package | ~~FullSWOF overland flow simulator~~TISEAN: Nonlinear Time Series Analysis]] || [[User:KaKiLa| KaKiLa]] || ? || Octave Forge || ~~Yes ~~[[TISEAN_package | No]] || Medium || ~~Never~~GSoC 2015

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~TISEAN_package ~~Octave_Package_management | ~~TISEAN: Nonlinear Time Series Analysis~~Octave Package management]] || Sebastian Schöps || [[User:KaKiLa|KaKiLa]] , Carnë Draug, Carlo de Falco || ~~? || Octave Forge |~~Infrastructure | ~~[[TISEAN_package ~~| ~~No]] ~~Yes || Medium || ~~GSoC 2015~~Never

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~Octave_Package_management ~~Symbolic_package | ~~Octave Package management~~Symbolic package]] || ~~Sebastian Schöps ~~Colin B. Macdonald || ~~[[User:KaKiLa|KaKiLa]]~~Mike Miller, ~~Carnë Draug, Carlo de Falco ~~Abhinav Tripathi || ~~Infrastructure ~~Octave Forge || ~~Yes ~~[https://github.com/cbm755/octsympy Octsympy] || Medium || ~~Never~~GSoC 2016

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~Symbolic_package ~~OCS | ~~Symbolic ~~OCS package]] || ~~Colin B. Macdonald ~~Sebastian Schöps || ~~Mike Miller, Abhinav Tripathi ~~Sebastian Schöps || Octave Forge , Numerical || ~~[https://github.com/cbm755/octsympy Octsympy] ~~Yes || ~~Medium ~~Easy || ~~GSoC 2016~~Never

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~Interval_package ~~Using_Python_within_Octave | ~~Interval ~~Pythonic package]] || ~~[[User:oheim~~Mike Miller |~~Oliver Heimlich]] || [[User:Siko1056~~|~~Kai T~~Colin B. ~~Ohlhus]] ~~Macdonald, Abhinav Tripathi || ~~Octave Forge, Numerical ~~Infrastructure || No || Medium || ~~[https://gsocinterval.blogspot.de/ ~~some in GSoC ~~2017]~~2016

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~OCS ~~JSON_encoding.2Fdecoding | ~~OCS package~~JSON encoding/decoding]] || ~~Sebastian Schöps ~~[[User:Siko1056|Kai T. Ohlhus]] || ~~Sebastian Schöps ~~? || ~~Octave Forge, Numerical ~~Infrastructure || Yes || ~~Easy ~~Medium || Never

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~Using_Python_within_Octave ~~Jupyter_Notebook_Integration | ~~Pytave project~~Jupyter Notebook Integration]] || Mike Miller || Colin B. Macdonald, ~~Abhinav Tripathi ~~[[User:Siko1056|Kai T. Ohlhus]] || Infrastructure || ~~No ~~ Yes || Medium || ~~some in GSoC 2016~~Never

|-

| [[~~Summer_of_Code_Project_Ideas~~Summer of Code - Getting Started#~~Jupyter_Integration ~~Chebfun_in_Octave | ~~Jupyter integration~~Chebfun in Octave]] ~~|| Mike Miller ~~|| Colin B. Macdonald~~, Ankit Raj ~~|| [[User:KaKiLa|KaKiLa]] || Infrastructure , Numerical || Yes ~~Yes ~~|| ~~Medium ~~Hard || Never

|-

| [[~~Summer_of_Code_Project_Ideas#Chebfun_in_Octave | Chebfun in Octave]] || Colin B. Macdonald || [[User:KaKiLa|KaKiLa]], Ankit Raj, needs core~~Summer of Code -~~Octave mentor/comentor || Infrastructure, Numerical || Yes || Hard || Never~~~~|-~~~~| [[Summer_of_Code_Project_Ideas#GUI Variable Editor and Property Inspector | GUI Property Inspector]] || ? || || GUI || Yes || Medium || Never~~~~|-~~~~| [[Summer_of_Code_Project_Ideas#SPQR Interface | Write API to SPQR Library]] || ? || || Infrastructure || Yes || Medium || Never~~~~|-~~~~| [[Summer_of_Code_Project_Ideas~~Getting Started#PolarAxes and Plotting Improvements | PolarAxes and Plotting Improvements ]] || ? || Rik || Graphics || Yes || Medium || Never

|}

These projects involve implementing certain mathematical functions, primarily in core Octave.

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

[http://hg.savannah.gnu.org/hgweb/octave/file/4890b1c4a6bd/scripts/ode/ode15i.m ode15i.m] and

[http://hg.savannah.gnu.org/hgweb/octave/file/4890b1c4a6bd/scripts/ode/ode15s.m ode15s.m].

The list of ~~outsanding ~~outstanding tracker tickets concerning this implementation can be found

[https://savannah.gnu.org/search/?Search=Search&words=ode15&type_of_search=bugs&only_group_id=1925&exact=1&max_rows=25#options here]

to a possible project plan would be improving documentation and tests in odepkg and removing

overlaps with the documentation in core Octave.

* '''Required skills'''

: Difficult.

* '''Potential mentors'''

: ~~Jordi Gutiérrez Hermoso~~Marco Caliari, Mudit Sharma

=== Improve iterative methods for sparse linear systems ===

GNU Octave currently has the following Krylov subspace methods for sparse linear systems: pcg (spd matrices) and pcr (Hermitian matrices), bicg,

bicgstab, cgs, gmres, and qmr (general matrices). The description of some of them (pcr, qmr) and their error messages are not aligned. Moreover, they have similar blocks of code (input check for instance) which can be written once and for all in common functions. The first step in this project could be a revision and a synchronization of the codes, starting from the project [~~http~~https://~~planet~~socis16octave-improveiterativemethods.~~octave~~blogspot.~~org~~com/~~#tag:blogger.com,1999:blog-1297699247151766814.post-8054019978706480250 ~~SOCIS2016]~~, whose latest patch, still to be included, ~~which is ~~[https://savannah.gnu.org/patch/?9108 here]~~already merged into Octave (cset {{cset|6266e321ef22}}).

In Matlab, some additional methods are available: minres and symmlq (symmetric matrices), bicgstabl (general matrices), lsqr (least

squares). The second step in this project could be the implementation of some of these missing functions.

The ~~reference book is available ~~[https://www-users.cs.umn.edu/~saad/IterMethBook_2ndEd.pdf ~~here~~reference book by Yousef Saad]is available online.

* '''Required skills'''

: Maybe hard the mathematical part, medium the programming part.

* '''Mentor'''

:Marco Caliari, Carlo de Falco

=== Chebfun in Octave ===

[~~http~~https://www.chebfun.org / Chebfun] is a mathematics and software project for "numerical computing with functions". Basically it approximates functions to machine precision accuracy (10<sup>-15</sup>) using piecewise Chebyshev polynomial interpolants. Operations on those functions (arithmetic, derivatives, root-finding, etc) are then overloaded and return new interpolating polynomials, which are themselves proxies for the actual solution.

Chebfun makes extensive use of classdef classes, and is one of the largest Free Software projects to do so. Unfortunately it currently only works in Matlab. This project seeks to (1) improve Octave's classdef support and (2) tweak Chebfun to work under Octave, for example, removing undocumented classdef features. The final goal is to have at least basic Chebfun features working on Octave. An additional goal would be making ~~"~~<code>pkg install chebfun.zip~~" ~~</code> work in Octave.

The impact of this project is improving Octave and allowing Chebfun to be used without proprietary software.

How to get started:

* Learn about [https://www.chebfun.org/ Chebfun]

* Browse [https://savannah.gnu.org/bugs/?group=octave Octave's bug list] for "classdef"-related bugs.

* Clone this Chebfun [https://github.com/cbm755/chebfun/tree/octave_dev octave_dev branch].

** On that, <code>f = chebfun(@(x) sin(x), [-2 6])</code> should work with Octave 4.3.0+ and maybe even with 4.2.1. Check that <code>f(pi)</code> and <code>g = f + 1</code> work.

** A good first task would be to study [https://github.com/cbm755/chebfun/commit/e20b0ad2dc89cfe8e50ba461b864eff7d5bbef17 this commit], a workaround for <code>f.funs{1}</code> using <code>temp = f.funs; temp{1}</code>. <code>2*f</code> is failing, can you fix it, perhaps with this workaround? Or can you make <code>f.funs{1}</code> work by changing something in <code>@chebfun/subsref.m</code>?

* '''Required skills'''

* '''Potential mentors'''

: Colin B. Macdonald, [[User:KaKiLa|KaKiLa]], Mike Miller (?), Carnë Draug (?), someone from Chebfun team (?).

== Adding functionality to Forge packages ==

Starting points

* [~~http~~https://www.~~univ-orleans~~idpoisson.fr/~~mapmo/soft/FullSWOF~~fullswof/ The FullSWOF Project].

* [https://arxiv.org/abs/1204.3210 FullSWOF: A software for overland flow simulation]

* [https://bitbucket.org/binello7/fswof2d Initial work on Bitbucket]

=== Symbolic package ===

Octave's [https://github.com/cbm755/octsympy Symbolic package] handles symbolic computing and other CAS 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. Recently, a GSoC2016 project successfully re-implemented this communication using the new [~~https://bitbucket.org/mtmiller/pytave Pytave tool~~[Pythonic|Pythonic package]].

This project proposes to go further: instead of using ~~Pytave ~~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 ~~Pytave ~~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 "f.diff(x)" instead of "diff(f, x)".

* '''Required skills'''

: OO-programming with m-files, Python, and possibly C/C++ for improving ~~Pytave ~~Pythonic (if needed).

* '''Difficulty'''

: easy/medium

* '''Mentors and/or other team members'''

: Colin B. Macdonald, Mike Miller, Abhinav Tripathi

=== OCS ===

[[Ocs package | OCS]] is a circuit simulator for Octave. The objective of this project is to update the code to use modern features of Octave (e.g. classdef), [https://savannah.gnu.org/search/?Search=Search&words=%28ocs%29&type_of_search=bugs&only_group_id=1925&exact=1&max_rows=25#options fix open bugs], increase compatibility with SPICE and improve compatibility with other Octave packages (odepkg, control etc).

* [http://octave.sourceforge.net/ocs/overview.html Package help at source forge.]

== Infrastructure ==

=== JSON encoding/decoding === [https://en.wikipedia.org/wiki/JSON JavaScript Object Notation], in short JSON, is a very common human readable and structured data format. Unfortunately, GNU Octave still lacks of builtin support of that data format. Having JSON support, Octave can improve for example it's web service functions, which often exchange JSON data these days. Another interesting applicatoin is described in another Octave GSoC project, see [[Summer of Code - Getting Started#Jupyter_Integration | Jupyter integration]]. In bug {{bug|53100}} a vivid discussion about proper JSON support took place. As JSON is a highly demanded feature for Octave, there are already several attempts to fill the gap: * [https://github.com/fangq/jsonlab jsonlab] (M-file implementation, probably slow for large JSON files)* [https://github.com/gllmflndn/JSONio JSONio] (C MEX wrapper around [https://github.com/zserge/jsmn jsmn])* [https://github.com/Andy1978/octave-rapidjson octave-rapidjson] (C++ Octave wrapper around [https://rapidjson.org/ RapidJSON])* [https://github.com/apjanke/octave-jsonstuff octave-jsonstuff] (C++ Octave wrapper around [https://rapidjson.org/ RapidJSON]) For different reasons, none of them can be directly merged into Octave core yet. Thus there is still lots of work to do. The goal of this project is to evaluate (and to cherry pick from) the implementations above, to create Matlab compatible [https://www.mathworks.com/help/matlab/ref/jsonencode.html jsonencode] and [https://www.mathworks.com/help/matlab/ref/jsondecode.html jsondecode] functions. This involves proper documentation of the work and unit tests to ensure the correctness of the implementation. * '''Minimum requirements''': Good Octave and C/C++ programming knowledge. Ability to make use of C/C++ libraries.* '''Difficulty''': Medium.* '''Mentor''': [[User:Siko1056|Kai T. Ohlhus]] === Jupyter Notebook Integration ===

[http://jupyter.org Jupyter Notebook] is a web-based worksheet interface for computing. There is a [https://github.com/Calysto/octave_kernel Octave kernel for Jupyter]. This project seeks in first place to improve that kernel to make Octave a first-class experience within the Jupyter Notebook.

In general the [https://nbformat.readthedocs.io/en/latest/ Jupyter Notebook Format] is a plain JSON document. In combination with another Octave GSoC project (see [[Summer of Code - Getting Started#JSON_encoding.2Fdecoding | JSON encoding/decoding]]), a second valuable outcome was that Octave can run (and fill) those Jupyter Notebooks on it's own. This would enable Jupyter Notebook users to evaluate long running Octave Notebooks on a computing server without permanent browser connection, which is [https://github.com/jupyter/notebook/issues/1647 still a pending issue].

* '''Minimum requirements'''

: Good Octave and Python programming knowledge.

* '''Difficulty'''

: Medium.

* '''Mentors'''

: Colin B. Macdonald, Mike Miller, ~~others?~~[[User:Siko1056|Kai T. Ohlhus]]

=== Using Python within Octave ===

[~~https://bitbucket.org/mtmiller/pytave Pytave~~[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. ~~Ideally, Pytave will ~~Pythonic may eventually not be a separate ~~project~~package, but rather a core feature of Octave. This project aims to improve ~~Pytave ~~Pythonic with the goal of ~~merging ~~making the ~~code into the core Octave code base~~package more stable, maintainable, and full-featured. ~~ ~~

Based on a previous summer project related to ~~Pytave~~Pythonic, this work will consist of fast-paced collaborative software development based on tackling the [https://~~bitbucket~~gitlab.~~org~~com/mtmiller/~~pytave~~octave-pythonic/issues~~?status=new&status=open pytave ~~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 ~~decision ~~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?

* '''Mentors'''

=== Octave Package management ===

[[Packages]] are extensions for Octave, that are mainly maintained by the [[Octave Forge]] community.To get those extension to work with Octave ~~management of installed packages ~~, there is ~~performed by ~~a single function, {{~~codeline~~manual|pkg}}, which does pretty much everything. This function has a few limitations which are hard to implement with the current codebase, and will most likely require a full rewrite.A major step forward for a rewritten package manager is the [https://github.com/apjanke/octave-packajoozle/ "packajoozle" project] by Andrew Janke.

The planned improvements (see also {{bug|39479}}) are:

* install and update from repositories (hg and git)

* automatic handling of dependencies

* support for multiple Octave installs

* support for system-wide and user installed packages

* testing packages (<code>pkg test <package-name></code>)

* improved metadata acquisition (<code>pkg list -forge</code>) from https://octave.sourceforge.io/

The main objective of this project is to make {{~~codeline~~manual|pkg}} more user friendly and to make it a tool to foster third party participation in Octave.~~{{codeline|pkg}} needs to be more flexible and intelligent when dealing with packages, different verisons and different sources, as well as options on how to build and install the package.~~~~There are also advance features of pkg that are useful for testing packages. ~~However, the current {{~~codeline~~manual|pkg}} also performs some maintenance functions which it probably should not.

Instead a package for developers should be created with such tools.

To do this enhancement effectively, a refactoring of the current {{codeline|pkg}} code will be needed (see [https://github.com/apjanke/octave-packajoozle/ "packajoozle" project]).

In addition, package names may start to collide very easily. One horrible way to workaround this by is choosing increasingly complex package names that give no hint on the package purpose. A much better is option is providing an Authority category like Perl 6 does. Nested packages is also an easy way to provide packages for specialized subjects (think {{codeline|image::morphology}}). A new {{~~codeline~~manual|pkg}} would think all this things now, or allow their implementation at a later time. Read the [[OEP:pkg|unfinished plan]] for more details.

* '''Minimum requirements'''

: Ability to read and write Octave code, experience with Octave packages, and understanding of the basics of autotools. The most important skill is software design.

* '''Difficulty'''

: ~~Easy to ~~Medium.

* '''Mentor'''

: [[User:KaKiLa|KaKiLa]], Carnë Draug, Carlo de Falco, Sebastian Schöps

== Image Analysis ==

* '''Potential mentor'''

: Carnë Draug

== Graphics ==

=== 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 listerners to get things to work. What is needed is a first class implementation of a "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" exist 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. relates to {{bug|35565}}, {{bug|49804}}, {{bug|52643}}.

* '''Minimum requirements'''

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