Scilab: An Interview with Sylvestre Ledru

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Scilab is one of the most popular FLOSS projects in the scientific computing area, in part due to its longevity, continuous development and community support. In this interview, Sylvestre Ledru, Scilab developer and operation manager for Scilab Enterprises, shares with us Scilab’s history and future. Enjoy!

F4S: Hi Sylvestre. Please, give us a brief introduction about yourself.

First, thanks for this interview and the work you are doing. I am a daily reader of your blogs and interviews.

My name is Sylvestre Ledru. I am French and, as most of the Scilab team, living in Paris or neighborhood. I have been working on Scilab for the last 6 years and witnessed the various mutations of the consortium and software.

After two years at Inria, 3.5 years at Digiteo Foundation, I am now part of Scilab Enterprises as operation manager (both for customers and research and development projects).

Besides that, I am also involved in IRILL, (the French Innovation and research initiative for free software) and in Debian, in particular in Debian Science team (which I co-founded a few years ago).

F4S: What is Scilab?

Scilab is numerical computing software. It can be seen as a Swiss-army knife for science. Scilab can be used as a powerful calculator (I use it to compute my tax forms) or to design rockets.

Simulations with (Xcos), graphic plotting or many other features are also available (the full list is too long).

Scilab is also a programming language with it own syntax, with very large capabilities and features.

F4S: Why and when did Scilab come to be?

It is a (very) long story. It started basically at the same period as Matlab to promote the research of researchers at Inria in France.

In the 80′s, Inria decided to publish it under the name Basile with the sources (at this time, free software was not what it is now).

Scilab became more and more popular. That is why Inria decided to create a consortium in 2003 to support Scilab and ensure a more industrial oriented development. After 4 years, Digiteo was founded to improve, document and stabilize the software. Scilab Enterprises was founded in 2010 to provide the, now usual, free software business model on Scilab.

Scilab is supported since 2003 by the Consortium which includes industrial and academics (

In June of this year, Scilab Enterprises will be the only responsible for Scilab development. Therefore, you could consider Scilab Enterprises as the main sponsor of Scilab.

Scilab Enterprises has also many important customers, mainly big corporations in the industrial field (aerospace, aeronautics, cars , etc) but also SME. We are also funded through R&D projects.

F4S: In which language(s) and platform(s) is the project developed?

Most of the code is written in Scilab (about 40 %).

In the 5.X family, the kernel is mainly Fortran and C (do not forget that the development started almost 30 years ago), but it has been redeveloped in C++ for the 6.X.

Around the kernel, you will find mainly C and Fortran.

The graphical user interface (GUI) is in Java which greatly simplifies the maintenance and portability of the software.

You will also find some Ocaml, Bash, some Tcl/Tk, etc. We try to use the appropriate language for the right task.

Scilab is available and supported under Windows XP, Vista, 7 (32 and 64 bits), Mac OS X and GNU/Linux (32 and 64 bits).

F4S: How many users you estimate Scilab have?

As you all know, with free software, it is hard to count the number of users. Scilab is freely available, duplicated on many mirrors or packaged in all distributions. It makes hard to keep track of users.

Moreover, our big customers are using their deployment infrastructure to install Scilab.

Anyway, we estimate that we have about a million users from all over the world.

F4S: Do you know where is Scilab used?

I cannot give a list of all our customers but Dassault Aviation, CNES (the French NASA), Arcelor Mittal, Valeo, Renault or PSA are among them. Besides our customers, we know that we are used in banks, public sectors (most of the French military agencies), etc.

Most of the French universities or Grandes Écoles (Ecole Centrale de Paris for example) are now teaching applied maths with Scilab instead of other proprietary software.

For example, we are really proud to say that Scilab is used to measure the stress the engine of the Airbus A320 Neo or to help designing the next space launchers.

As you can see, the list is long!

F4S: How many team members does the project have?

We are more than 10 people working full time on Scilab and we are currently looking for 7 new engineers or mathematicians.

Besides that, we benefit from the support of a strong and important community. Many people are improving Scilab itself, the documentation, the localization (Scilab 5.4.0 will be released with at least 14 translations), the external modules, etc.

We have been also involved for four years in the Google Summer of Code project which brings every year new contributors.

F4S: In what areas of Scilab development do you currently need help?

While we improved a lot in this field, we still need help with Scilab documentation . Some help pages are unclear, with frenglish (french-english) or missing examples.

Any contribution on it is very much welcomed! So do not hesitate to send us reports, proposals or patches! We usually apply patches very quickly!

Otherwise, external modules for Xcos, our simulator, are more than welcomed.

F4S: How can people get involved with the project?

It depends on the skill of the contributors but usually, starting with bug fixes or documentation improvements are nice and not-that-hard way to begin with.

The process is clearly documented and pretty easy. Scilab team is automatically warned of all bug reports. Therefore, if you send any patches through the bug report, we will see them and try to apply them. Interested people can also have a look to our list of ideas.

F4S: What features are in the roadmap?

Scilab 5.4.0, which will be released very soon, is going to be just great. (F4S: Scilab 5.4 preview)

Continuing our user-oriented efforts, we are happy to introduce Scilab Desktop. Basically, the docking system is now able to keep the position, information and size from a session to the other. That means that variable browser or editor, Xcos, help browser, etc will be available just like the last time you used Scilab.

Besides that, we introduced both read and write full and easy-to-use XML features into Scilab.

Xcos and Javasci (our Java API to use Scilab as a computing engine) are now way faster.

And finally, we greatly improved the portability and the speed of the Scilab graphic (from 4 to 10 times the speed of the graphic in the version 5.3.3).

In parallel, strong efforts are done to develop Scilab 6 release which represents a huge step for Scilab. With Scilab 6, w will be able to address the whole memory of a system without any lag (we tested with 32 gb matrices). The code is way easier to get into, to hack or to maintain.

We will be able to propose out-of-the-box parallel computation, Just-in-time, etc.

F4S: Which projects, blogs or sites related to open source software for science can you recommend?

Yours of course ! ;)

(F4S: Well, thank you!)

F4S: Why do you consider free/libre open source software important for the advancement of your field?

A quote taken from the Science Code Manifesto resumes our engagement for open source software:

“Software is a cornerstone of science. Without software, twenty-first
century science would be impossible. Without better software, science
cannot progress.”

I believe that FLOSS is critical in such field. It is necessary to have the potential to analyse the full software stack, and thus for two main reasons:

  • Being able to investigate which algorithms have been used and how they were implemented
  • Independence from the editor. If the editor dies, changes the term of usages or prices, it breaks the capability to replay the computation in the future.

F4S: Where people can contact you and learn more about Scilab?

About Scilab, the two official websites:

I can also be reached at

F4S: Thank you for your time Sylvestre. Here is a video of Sylvestre giving a talk about Scilab extendability at the GNU Hackers Meeting 2011.

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  3. Scilab Image Processing Toolbox 0.7.0 released
  4. An interview with Equalis, a Scilab based business