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David
上次活动时间: 2023-10-31

See what's going on at MATLAB Central without leaving MATLAB 🙂

Here's a MATLAB class I wrote that leverages the MATLAB Central Interface for MATLAB toolbox, which in turn uses the publicy available Community API. Using this class, I've created a few Favorites that show me what's going on in MATLAB Central - without having to leave MATLAB 🙂

The class has a few convenient queries:

Results for the last 7 days
Results for the last 30 days
Results for the current month
Results for today

And supporting a bunch of different content scopes:

All MATLAB Central
MATLAB Answers
Blogs
Cody
Contests
File Exchange
Exclude Answers content

The results are displayed in the command window (which worked best for me) and link to each post. Here's what that looks like for this command

>> CommunityFeed.thisMonth("app designer", CommunityFeed.Scope.ExcludeAnswers)

Let me know if you find this class useful and feel free to suggest changes.

Tips & Tricks

Ben Pasquariello
上次活动时间: 2023-10-25

New Cheat Sheet for Organizing and Accessing Data in MATLAB

New Cheat Sheet Alert!

Level up your data organization and access skills in MATLAB with our latest cheat sheet! Download the full cheat sheet on MATLAB GitHub for Students here.

Highlights

Adam Danz
上次活动时间: 2023-12-9

Why do you save figure (.fig) files?

I rarely/never save .fig files

47%

Continue working on it later

16%

Archive for future reference

23%

Share within my organization

10%

Share outside my organization

Other (please leave a comment)

2097 个投票

Ideas

Julian
上次活动时间: 2024-2-5

Naming x-values in bar(x,y)

I know the latest version of MATLAB R2023b has this feature already, put it should be added to R2023a as well because of its simplicity and convenience.

Basically, I want to make a bar graph that lets me name each column in a basic bar graph:

y=[100 99 100 200 200 300 500 800 1000];

x=["0-4" "5-17" "18-29" "30-39" "40-49" "50-64" "65-74" "75-84" "85+"];

bar(x,y)

However, in R2023a, this isn't a feature. I think it should be added because it helps to present data and ideas more clearly and professionally, which is the purpose of a graph to begin with.

General

Kilsu Kim
上次活动时间: 2023-10-19

Just for Fun and Curiosity: Guess the MATLAB Compile Threshold on Windows

Recently, I came across a post about the JIT compiler on this Korean blog. In the post. The writer discussed the concept of the "Compile Threshold" and how it is calculated.

"The JVM accumulates the number of calls for each method called and compiles when the number exceeds a certain number. In other words, there is a standard for checking how often it is called and then deciding, 'It is time to compile.' This standard is called the compilation threshold. But what is this and why should it be used as a standard?"

The concept of the "Compile Threshold," as used above, seems to be more commonly associated with Tracing just-in-time compilation.

The writer used the simple Java code below to calculate the threshold.

for (int i = 0; i < 500; ++i) {
  long startTime = System.nanoTime();
  for (int j = 0; j < 1000; ++j) {
 	new Object();
  }
  long endTime = System.nanoTime();
  System.out.printf("%d\t%d\n", i, endTime - startTime);
}

Since the MATLAB execution engine uses JIT compilation, I just wanted to perform the same experiment that the writer did.

I experimented using simple codes based on the code in the blog. I iterated a function 500 time using for-loop and calculated the execution time for each iteration using tic and toc. Then I plotted the execution time for each loop as blow. First five execution times are much higher than followings (10 times!) The test is very rough so I am not sure that I can conclude "MATLAB has Compile Threshold and it is 5!" but this value is actually correct ;-)

t0 = 0;
tfinal = 10;
y0 = [20;20];
timeToRun = zeros(500,1);
for i = 1:500
    tStart = tic;
    [preypeaks,predatorpeaks] = solvelotka(t0, tfinal, y0);
    tEnd = toc(tStart);
    timeToRun(i) = tEnd;
end

General

Toshiaki Takeuchi
上次活动时间: 2023-10-23

Do you use VS Code for writing MATLAB Code?

VS Code Extension for MATLAB was introduced back in April and has been downloaded 75K times since. Do people here use VS Code for writing MATLAB code?

vs code

Ideas

Matt J
上次活动时间: 2024-3-1

Implicit expansion for CAT()

Would it be a good thing to have implicit expansion enabled for cat(), horzcat(), vertcat()? There are often situations where I would like to be able to do things like this:

 x=[10;20;30;40];
 y=[11;12;13;14];
 z=cat(3, 0,1,2);
 
 C=[x,y,z]
 

with the result,