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goc3
Last activity il 6 Nov 2023

Don't Reinvent the Wheel

Have you ever learned that something you were doing manually in MATLAB was already possible using a built-in feature? Have you ever written a function only to later realize (or be told) that a built-in function already did what you needed?

Two such moments come to mind for me.

1. Did you realize that you can set conditional breakpoints? Neither did I, until someone showed me that feature. To do that, open or create a file in the editor, right click on a line number for any line that contains code, and select Set Conditional Breakpoint... This will bring up a dialog wherein you can type any logical condition for which execution should be paused. Before I learned about this, I would manually insert if-statements during debugging. Then, after fixing each bug, I would have to delete those statements. This built-in feature is so much better.

2. Have you ever needed to plot horizontal or vertical lines in a plot? For the longest time, I would manually code such lines. Then, I learned about xline() and yline(). Not only is less code required, these lines automatically span the entire axes while zooming, panning, or adjusting axis limits!

Share your own Aha! moments below. This will help everyone learn about MATLAB functionality that may not be obvious or front and center.

(Note: While File Exchange contains many great contributions, the intent of this thread is to focus on built-in MATLAB functionality.)

Moja
Last activity il 13 Ott 2023

caret on macbook pro

The carot symbol on my keyboard (ˆ shift+6) doesn't work on matlab. Matlab doesn't recognize it so I can't write any equation with power symbol. I tried every possible solution on the web and it doesn't work. even in the character viewer I don't have any result when I search ''caret".

https://www.mathworks.com/academia/student-challenge/simulink-student-challenge-2023.html

Ben Pasquariello
Last activity il 12 Ott 2023

Simulink Student Challenge 2023 is live!

Exciting news for students! 🚀Simulink Student Challenge 2023 is live! Unleash your engineering skills and compete for exciting rewards. Submission deadline is December 12th, 2023!

Adam Danz
Last activity il 13 Ott 2023

Approximating π with durations

Over the weekend I came across a pi approximation using durations of years and weeks (image below, Wolfram, eq. 89), accurate to 6 digits using the average Gregorian year (365.2425 days).

Here it is in MATLAB. I divided by 1 week at the end rather than multiplying by its reciprocal because you can’t divide a numeric by a duration in MATLAB (1/week).

weeks = @(n)n*days(7);
piApprox = ((years(13)-weeks(6))/years(13) + weeks(3)) / weeks(1)
% piApprox = 3.141593493469302

Here’s a breakdown

The first argument becomes 12.885 yrs / 13 yrs or 0.99115
Add three weeks: 0.99115 + 3 weeks = 21.991 days
The reduced fraction becomes 21.991 days / 7 days

Now it looks a lot closer to the more familiar approximation for pi 22/7 but with greater precision!

https://www.youtube.com/watch?v=h376W93gQq4

Walter Roberson
Last activity il 6 Ott 2023

full body keyboard using flag semaphore

This person used computer version to build a keyboard input, and used standard flag semaphore for the positions.

Flag semaphore is used mostly by sailors to be able to communicate optically over a distance; it does not need anything more than make-shift flags (but binoculars or telescopes can help.) Trained users can go faster than you might guess.

Hans Scharler
Last activity il 27 Lug 2024

What's everyone doing today?

Chen, Rena, and I are at a community management event. It's great to be with others talking about relationships, trust, and co-creation.

community

Chen Lin
Last activity il 16 Ott 2023

The Community Snacks!

I'm in a community conference in Boston today and see what snacks we get! The organizer said it's a coincidence, but it's definitly a good idea to have them in our MathWorks community meetings.

community

https://www.youtube.com/watch?v=UTUnVEiO-TU

Walter Roberson
Last activity il 27 Dic 2023

Tricking AI vision systems

A research team found a way to trick a number of AI systems by injecting carefully placed nonsense -- for example being able able to beat DeepMind's Go game.

https://www.youtube.com/watch?v=SsGEcLwjgEg

Walter Roberson
Last activity il 4 Ott 2023

"Cody" bridge rotates up to move out of the way

This video discusses the "Cody" bridge, which is a pedestrian bridge over a canal that has been designed to move up and out of the way when ships need to travel through. The mathematics of the bridge movement are discussed and diagrammed. It is unique and educational.

https://fb.watch/njjZFdCnC1/

Walter Roberson
Last activity il 4 Ott 2023

touch microscope developed

Recently developed: a "microscope" based on touch and stereo vision.

Using touch removes the possibility of optical confusion -- for example, black on touch is only due to shape, not due to the possibility that the object has a black patch.

Sorry, you might need a Facebook account to watch the video.

Image Analyst
Last activity il 3 Ott 2023

The new release is here!

(Sorry - it should be 2023b by now.)

Mike Croucher
Last activity il 10 Maggio 2024

spy easter egg

spy

Adam Danz
Last activity il 6 Mar 2024

To hold or not to hold

I'm curious how the community uses the hold command when creating charts and graphics in MATLAB. In short, hold on sets up the axes to add new objects to the axes while hold off sets up the axes to reset when new objects are added.

When you use hold on do you always follow up with hold off? What's your reasoning on this decision?

Can't wait to discuss this here! I'd love to hear from newbies and experts alike!

graphics

Mike Croucher
Last activity il 3 Ott 2023

Totally new solution framework for Ordinary Differential Equations (ODEs) in MATLAB

The way we've solved ODEs in MATLAB has been relatively unchanged at the user-level for decades. Indeed, I consider ode45 to be as iconic as backslash! There have been a few new solvers in recent years -- ode78 and ode89 for example -- and various things have gotten much faster but if you learned how to solve ODEs in MATLAB in 1997 then your knowledge is still applicable today.

In R2023b, there's a completely new framework for solving ODEs and I love it! You might argue that I'm contractually obliged to love it since I'm a MathWorker but I can assure you this is the real thing!

I wrote it up in a tutorial style on The MATLAB Blog https://blogs.mathworks.com/matlab/2023/10/03/the-new-solution-framework-for-ordinary-differential-equations-odes-in-matlab-r2023b/

The new interface makes a lot of things a much easier to do. Its also setting us up for a future where we'll be able to do some very cool algorithmic stuff behind the scenes.

Let me know what you think of the new functionality and what you think MathWorks should be doing next in the area of ODEs.

Rena Berman
Last activity il 11 Ott 2023

PUZZLE: MATLAB-related word scramble

To solve the puzzle, first unscramble each of the words on the left. Then rearrange the letters in the yellow shaded boxes to complete the sentence on the right.

If you enjoyed this puzzle let me know with a like or in the comments below and I'll post more of them. Please don't post your answer, or any hints, and spoil it for those who come across this puzzle after you!! If you want to check your answer, you can messge me your guess through the link on my profile card (click on my name, Rena Berman, above and then on the envelope icon in the top right corner of the profile card that appears).