# Community Q&A – Akrem Hadji

Akrem Hadji is a top contributor to Cody.  Here is a Q&A I did with Akrem who is a Telecommunications Engineer in Tunisia.

Thanks for agreeing to this interview.  When did you first get exposed to MATLAB and did you start using it right away, or did it take a while to grow on you?

I started using MATLAB in 2012, during my engineering studies. We used MATLAB in class for signal processing. I recall the first exercise was to make an array of “Dirac'' pulses. After that, every lesson was a new opportunity to explore more tools. My skill has improved with time. In the beginning I remember that the MATLAB language was very practical with an arsenal full of all the needed functions. By the end of the first year in engineering, I was accustomed to use MATLAB in linear algebra, calculus, signal processing, optimization algorithms and more.

As a software developer do you still use MATLAB?

I am a MATLAB user by nature, I usually implement algorithms and analyze results. Nevertheless, I believe coding skill must include the knowledge of debugging and handling errors. Sometimes I cannot separate one from another. A software developer should understand how his machine runs his code.

Tell me about something interesting you have done with MATLAB.

I built an indoor WIFI signal strength estimator. To achieve it, I used an indoor house plan as input. Then I transformed it into a matrix of coefficients according to the electromagnetic absorption of the corresponding materials (walls, glass, wood ...). Finally, I estimate the power of receiving WIFI signals transmitted from a fixed hotspot in the different rooms of that house by using the finite element theory.

Above is a picture of the input Matrix (radio power absorption).  In this picture we can distinguish:

• The rooms (walls are represented in yellow with different thickness)
• The corridors
• The elevators, red rectangles, have the highest absorption coefficient

The output picture of simulation above represents an estimation of the received signal:

• Generally the power is evaluated in dBm by negative values, but here I represented them in the positive range.
• The WIFI hotspot is supposed to be an omnidirectional antenna
• The simulator evaluates the shadowing applied on the line of sight, but does not analyze the possible reflections. This particular point could be a possible improvement target to be realized.
When did you first decide to participate in MATLAB Central?

I joined MATLAB Central last year to participate in the Cody Challenge. It was an appealing opportunity for me to join a network of MATLAB users to share and participate in this event.

You did a great job participating in the Cody Challenge with an impressive 4th place finish.

It was a hard competition, especially during the last days of the challenge. Unfortunately, I couldn’t keep up with the top three scorers.

I read an article once that describes how getting second place feels bitter usually in similar competitions. In my case, in the beginning I was frustrated with my 4th place finish. The competition was tough, each point counts until the last moment.

Now, when I look back to evaluate, I see that I did my best.  The competition was tough and I had a lot of other things going on.  Still I put forth a huge effort to reach my score, thus I am totally satisfied with the result.

What are the greatest benefits you get out of using Cody?

The challenge helped me to refresh my memory using a lot of MATLAB’s functions. Some problems were very challenging to resolve and frankly I enjoyed solving them the most.

Furthermore, I made new friends thanks to the Cody challenge. I’ve received several questions from MATLAB users in some subjects and I helped them. I also got in touch with Lincoln Poon, my Cody “rival,” and we discussed the score evaluation at the end of the challenge. To be honest, he even proposed to share the 3rd place prize with me, but I reject his offer because I think he deserved it. I believe the Cody challenge was a long run race like the Olympics’ marathon instead of a 26 mile run, we have three months to resolve problems restlessly.

Do you have a favorite Cody Problem?

I recommend Problem 752. Is X a Fibonacci Matrix? , by Sean de Wolski, because it reintroduces the famous Fibonacci sequence with an elegant generalized approach. It is a problem that offers a wide understanding of the sequence philosophy, the practicality of matrix multiplication and it’s fun to solve. (The whole package)

What about a favorite Cody Problem Group?

The Advanced Level Problem Group Project Euler I.  I am very glad I was able to participate in solving these advanced problems. Accomplishing a problem group motivates you to resolve more.

I consider this group as a high advanced problem set. The resolution of those problems requires combined skill both in coding and in mathematics. The motivation of resolving these problems is driven by the desire to climb high obstacles. The Project Euler is not made for those who give up easily. I recommend it for those who have previous experience in solving problems.

What’s the number one piece of advice you would give to someone to improve their Cody problem?

The problem should be well explained in the description and the test set should be composed of a wide range of possible examples.

What do you think is the most valuable resource on MATLAB Central?

MATLAB Answers is by far the most important resource in MATLAB Central. It’s very handy for coders to reuse or modify given solutions from previous questions. This asset is a huge time saver for developers.

What’s the most surprising thing you’ve come across on MATLAB Central?

The Toolbox Library is by far the most surprising MATLAB Central component. I spend a lot of time downloading and testing other member's contributions. It's a very helpful and time saving tool for others members to reuse.

What keeps you coming back to MATLAB Central?

MATLAB Central is the platform that promotes and inspires all MATLAB users. I have a deep passion toward MATLAB and by participating in the community I feel that my contribution has a great value. The concept of sharing knowledge and skills to encourage community members to come up with new ideas and resolve challenging problems has always been my ultimate goal.

What’s one of your favorite non-software non-mathematical things to do?

Before the lockdown, I used to go hiking with friends and explore new places. I enjoyed spending time far away from my city.

Unfortunately, since last year I had to switch my hobby to something else. Now I follow an online aerobics class. I have volunteered in translation working groups; I translate scientific articles into Arabic for “IEEE Arabic” and “Researchers bahisoon” to enrich the online Arabic scientific content and to inspire youngsters in the region to seek knowledge.

What kinds of books do you enjoy reading?

I generally prefer political books, I love reading books related to the common human life experiences.

My favorite novel is Nineteen Eighty-Four, by George Orwell. This masterpiece has had a huge impact on my personal perceptions. I lived in a country that suffered from a long time of oppression. Each time I read this book I automatically find a relatable link between what’s written, and how life felt back then. The brilliant writer created a universe in his story that fits the best life during those times.

Any other books you enjoy?

I actually have a book idea for myself that I dream of publishing someday. The book will be about the architecture of house's roof shapes. I noticed that the triangular shape of a house's roof comes with a wide range of angles on its tops. The idea is to compare those angles from different regions, countries and even continents, if it's possible. Especially old traditional houses.

The aim of this book will be to prove an idea that has been chasing me  for a long time. We humans are adaptable creatures to our environment, and when we build our houses we will make sure to make them resistant to local weather. This angle would be smaller in snowier places on earth (Sweden and Switzerland), and wider in hotter places (southern Italy and Greece).

l love finding and understanding patterns in general. This project could be a way to give us a view on house’s roof angles to earth’s weather as a scalar field. It’s a tremendous work that requires a lot of time and energy, I hope I realize it some day.

Is there a quote that has inspired your enthusiasm for knowledge?

“Limited in his nature, infinite in his desires, man is a fallen god who remembers the heavens.”

― Alphonse de Lamartine: Méditations Poétiques

|