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A: An introduction
- Please describe yourself in three sentences, one of them regarding your current studies.
- My name is Joel Dahne and I am a first year student at the master program in mathematics at Uppsala University, Sweden, where I also did my bachelor in matematics. I am from Sweden, so naturally speak Swedish, but all my current studies are in english so I am used to that as well. Apart from mathematics I have a great intereset in computer science which always is a motivation when taking new courses in mathematics.
- Why do you want to participate in the Google Summer of Code? What do you hope to gain by doing so?
- I have done quite a lot of programming but mostly it has been shorter projects, testing a new language, creating some small program or similar. The biggest project I have done was during my bachelor project where I create a program to isolate zeros for systems of two analytic functions. I really enjoyed that project and I want to do something similar again.
- Please also describe your previous experience with the GSoC, if any.
- First time I heard about GSoC was last summer so I have no experience from previous years.
- Why are you choosing Octave?
- The first time I heard about GSoC was at SWIM2016, a conference about methods in interval analysis that year taking place in Lyon. One of the speakers were Oliver Heimlich who spoke about the interval package in Octave. I was very interested in his work and I remember he mentioned that they had been looking for GSoC students to work with the package last year. Because of that I thought about Octave when I looked at this years accepted organizations.
- Please state the (unique and identical where possible) nick you use on IRC and any other communication channel related to Octave.
- The nick I will be using is Urathai and you can find me on other channels with that as well, for example GitHub [].
- Which time zone do you live in? Will that change over GSoC duration?
- The time zone I live and work in is UTC+2, including DST adjustments, and will stay so for the duration of the project
- Please state the timeframe (in UTC+0) when you feel most comfortable working during GSoC. Where are your time buffers?
- With all timeframes in UTC+0 I usually work between 7.00 to 16.00 but I have no problem working later, or even a bit earlier, if needed.
E: Coding experience
This part is one of the more important ones in your application. You are allowed to be as verbose as you want, as long as you stay on topic ;-)
- Please describe your experience with C++, Octave or Matlab m-scripts, OpenGL and Qt.
- I have quite a lot of experience with C++, especially in terms of scientific computing. This comes mainly from my bachelor project where I implemented a program for isolating zeros to systems of two analytic functions, more about that further down.
- I first came accross Matlab in my Scientific Computing courses were I learned the basics. After I have used it several times for calculations and plotting in smaller projects. Since about a year ago I switched from using Matlab to Octave. I am aware of some of the pros and cons with the language, for example that if you want any kind of performance you should use vectorized functions instead of for-loops.
- For OpenGL and Qt I have no experience but I know the basics of what they are supposed to do and how.
- Please describe your experience with other programming languages.
- Over the years I have tried and used quite a lot of different programming languages. Most of my experience comes from smaller projects. For example solving Project Euler problems or writing a small interpreter for Brainfuck. Thus I have mostly used scripting-like languages like Python and Haskell. I have also taken courses in Java, but not really used it outside of that.
- Please describe your experience with being in a development team.
- Most of my programming have been personal projects so I have little experience from being in a development team, though this is something I really would like to do. On any larger project you are several people working together and I want to learn more about how I function in such situations.
- Please describe the biggest project you have written code for and what you learned by doing so. Also describe your role in that project over time.
- The biggest project I have worked on is, as mentioned, my bachelor project. It was my first big project and I have learned very much from it. I started on the project last spring and my object was to build a program that could isolate zeros to a system of two analytic functions. Since I am a mathematics student the goal was to have it generate validated results, both on the number of zeros and their locations. It was done using interval methods with the C-XSC package []. This was my first project were I used version control in a serious way. I did many mistakes at first, for example keeping track of binary files and making to large commits, but I learned a lot. I learned about optimizing and parallelizing. For some problems the program run for several days on multiple computers, so performance was very important. At first I wrote the program for myself only, no documentation and weird input and output. Later on I realized I also wanted other people to be able to use the program. This made me rewrite the whole input and output so that it would be easier to understand and use. Now, whenever I start a new project, even if it is just for me at the moment, I think about how I can make using the program easier for other people. The latest version of the project is available at GitHub, https://github.com/Urathai/generateZeros.
- Please state the commits and patches you already contributed to Octave.
- Fixed a bug in the dot product for intervals
- Implemented end-indexing for intervals 
F: Feeling fine
- Please describe (in short) your experience with the following tools:
- IRC and mailing lists
- I have not used IRC before, but it was easy to set up and I had no problem using it. Though I am used to mailing lists I am not used to development mailing lists. Sometimes I think it is a bit unclear what fits best on the IRC channel or the mailing list.
- Mercurial or other source code management systems
- I have used git for my personal projects and is familiar with that. Though I am not very experienced with using source code management for collaborating with many different people. Mercurial was easy to get going with but I will have to read a bit more about how it works in the background.
- Mediawiki or other wiki software
- I have no experience with Mediawiki other than writing this text.
- make, gcc, gdb or other development tools
- Both make and gcc I have used several times in different projects and I know how they work. gdb I have used only a handful of times.
- What will make you actively stay in our community after this GSoC is over?
- I think that the one thing that would make the most difference regarding if I stay or not is if people use the code I write. If people make use of it, ask questions and do bug reports I think I will have no problem finding motivation to continue. Also making new new friends and finding people to discuss with would probably get me to stay.
O: Only out of interest
- Did you ever hear about Octave before?
- If so, when and where? How far have you been involved already?
- The first time I encountered Octave was during a conference last summer, SWIM2016 [], were Oliver Heimlich presented his interval package. Since then I have been using it instead of Matlab but I have not contributed anything before this.
- What was the first question concerning Octave you could not find an answer to rather quickly?
- I tried to install Octave from source following the wiki documentation. [Octave_for_Debian_systems] Unfortunately this documentation is outdated and I had to manually track down some of the required dependencies which toke some time.
- Please state the operating system you work with.
- My normal operating system is Ubuntu 16.04, but I am also dual booting this with windows 10. Both of these I can access freely with no conditions.
- Please estimate an average time per day you will be able to access
- an internet connection
- a computer
- a computer with your progressing work on
- I will be able to access all of these at almost any time.
- Please describe the degree to which you can install new software on computers you have access to.
- Since it is my own computer I have no problem installing new software.
- Please describe how useful criticism looks from your point of view as committing student.
- I think that the most important part of useful criticism is explaining why they think something should or should not be done in a particular way and what they base that on. If I do not know why I do something I first of all wont remember it and secondly might not like it. When it comes to criticism over mail or other more static channels I think it is extra important to give references when possible. That way I can look up things myself if I need any more information.
- How autonomous are you when developing:
- Do you like to discuss changes intensively and not start coding until you know what you want to do?
- Do you like to code a proof of concept to 'see how it turns out', modifying that and taking the risk of having work thrown away if it doesn't match what the project or original proponent had in mind?
- How I work when developing depends on what I am doing. If I am trying to implement a new function or feature I prefer to do a quick proof of concept. Then take what I learned from the proof of concept and do a more rigid implementation. This is true especially if I am working in a for me new environment, I then find it hard to reason about the code without really knowing about the limitations.
- If instead I am trying to modify some already existing code I prefer to first try some really small modifications just to see if I understand the code. After that I want to pinpoint exactly what should be changed, what is the behavior of the code now and what behavior do we want after?
- It is important for me to get some kind of approval that I am going in the right direction. Thus I prefer to discuss quite a lot in the beginning of the project, but when I get more comfortable with it I can work more autonomous.
Y: Your task
- Did you select a task from our list of proposals and ideas?
- Sort of. My main interests lies in improving the interval package. The are a couple of listed possible projects, all of which sound interesting. I have have also thought about a different project, implementing Taylor arithmetic in Octave. I think that for the interval package to really shine it needs access to automatic differentiation, which could be done in the form of Taylor arithmetic. I have implemented a proof-of-concept for how this could work []. Though I am not sure if it is reasonable to implement a whole new Octave-forge package during GSoC and I am not sure who could mentor such a project, if this is interesting please let me know.
- The project I have looked most at is the one about implementing support for N-dimensional arrays of vectors. I think that this projects is important if we want to make working with intervals as natural as working with floating points in Octave. Below I give a rough possible time line for this.
- Community Bonding (May 4-30)
- First Term (May 30 - June 30)
- Week 1 (May 30 - June 2): Identify all functions that will need to be changed to support N-dimensional arrays.
- Week 2 (June 5-9): None-coding time
- Week 3-4 (June 12-23): Implement support for creating and displaying N-dimensional arrays.
- Week 5 (June 26-30: Evaluation
- Second Term (June 30 - July 28)
- Implement vectorized functions for N-dimensional arrays of intervals.
- Start implementing specific functions for N-dimensional arrays (whatever they are)
- Final Term (July 28 - August 29)
- Add examples and usage of N-dimensional intervals to the documentation. Documentation will probably be written in parallel to implementing the new functions, this time is for completing it and adding more usage examples.