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I created several problems recently in CODY. Some of them got removed automatically. I was curious as to why.
It is possible that the problems used latex in their description, so I am not sure if that was the reason they got rejected by the cody server.
Muhtasim Haque Nahian
Muhtasim Haque Nahian
Last activity 2021 年 5 月 27 日

My problems are vanished

I created some problems last night and created a group too. All those are now missing.
Also my ranking progress, activites, badges earned last night are missing too.
Tungky Subroto
Tungky Subroto
Last activity 2021 年 2 月 28 日

Cody challenges for Simulink ?

Hi all,
I hope everyone is doing well and keeping safe. I was wondering, are there any Cody challenges for Simulink these days?
I saw a post from 2015 (https://blogs.mathworks.com/simulink/2015/08/07/modeling-and-simulation-challenge-in-cody/) and it seems there was a Simulink or "Modeling and Simulation Challenge" problem group, but I couldn't find this group anymore. Perhaps I missing something?
Thank you beforehand.
Tungky

Happy New Year, everyone! We hope you enjoyed the Cody contest in 2020, learned new MATLAB skills, and made a friend or two. While the 2020 contest has concluded, the fun and learning never end.

Please take the 1-minute survey to talk about your experience (only 2 required questions). Our goal is to make future contests better and more appealing to you, so your feedback is critical to us.

Thank you in advance and hope to see you again in the 2021 contest.

I see this solution on the Cody solutions list. Solution 1949216
I am puzzled as to how this could possibly be rated as correct (size 48)
(BTW - I am pretty sure I saw this, or similar, before.)
function ans = fileread(varargin)
' ';
a=1;
b=3;
a=1;
b=3;a=1;
b=3;a=1;
b=3;a=1;
b=3; end
Chen Lin
Chen Lin
Last activity 2020 年 10 月 1 日

Cody Contest 2020 Starts Today!

We are excited to announce that Cody Contest 2020 starts today! Again, the rule is simple - solve any problem and rate its difficulty. If you have any question, please visit our FAQs page first. Want to know your ranking? Check out the contest leaderboard .

Happy problem-solving! We hope you are a winner.

Chen Lin
Chen Lin
Last activity 2021 年 1 月 23 日

Cody Contest 2020 FAQs

Below are some FAQs for the Cody contest 2020. If you have any additional questions, ask your questions by replying to this post. We will keep updating the FAQs.

Q1: If I rate a problem I solved before the contest, will I still get a raffle ticket?

A: Yes. You can rate any problem you have solved, whether it was before or during the contest period.

Q2: When will I receive the contest badges that I've earned?

A: All badges will be awarded after the contest ends.

Q3: How do I know if I’m the raffle winner?

A: If you are a winner, we will contact you to get your name and mailing address. You can find the list of winners on the Cody contest page .

Q4: When will I receive my T-shirt or hat?

A: You will typically receive your prize within a few weeks. It might take longer for international shipping.

Q5: I'm new to Cody. If I have some questions about using Cody, how can I get help?

A: You can ask your question by replying this post. Other community users might help you and we will also monitor the threads. You might also find answers here .

Q6: What do I do if I have a question about a specific problem?

A: If the problem description is unclear, the test suite is broken, or similar concerns arise, post your question(s) as a comment on the specific problem page. If you are having a hard time solving a problem, you can post a comment to your solution attempt (after submitting it). However, do not ask other people to solve problems for you.

Q7: If I find a bug or notice someone is cheating/spamming during the contest, how can I report it?

A: Use Web Site Feedback . Select "MATLAB Central" from the category list.

Q8: Why can't I rate a problem?

A: To rate a problem, you must solve that problem first and have at least 50 total points.

It's pretty odd how a solution that uses more characters than usual can be the "leading solution" of a Cody problem and have the least size. Compare these two codes that find the sum of integers from 1 to 2^x, which one uses fewer characters, thus should be the better solution?
function y = sum_int(x)
regexp '' '(?@y=sum(1:2^x);)'
end
function ans = sum_int(x)
sum(1:2^x)
end
Hans Scharler
Hans Scharler
Last activity 2021 年 10 月 1 日

Who is using the MATLAB Discord channel?

Is anyone using the MATLAB Discord channel?
Rik
Rik
Last activity 2024 年 9 月 17 日

What frustrates you about MATLAB? #2

Similar to what has happened with the wishlist threads (#1 #2 #3 #4 #5), the "what frustrates you about MATLAB" thread has become very large. This makes navigation difficult and increases page load times.
So here is the follow-up page.
What should you post where?
Wishlist threads (#1 #2 #3 #4 #5): bugs and feature requests for Matlab Answers
Frustation threads (#1 #2): frustations about usage and capabilities of Matlab itself
Missing feature threads (#1 #2): features that you whish Matlab would have had
Next Gen threads (#1): features that would break compatibility with previous versions, but would be nice to have
@anyone posting a new thread when the last one gets too large (about 50 answers seems a reasonable limit per thread), please update this list in all last threads. (if you don't have editing privileges, just post a comment asking someone to do the edit)
Even
Even
Last activity 2023 年 7 月 23 日

Problem 44951. Verify Law of Large Numbers

If a large number of fair N-sided dice are rolled, the average of the simulated rolls is likely to be close to the mean of 1,2,...N i.e. the expected value of one die. For example, the expected value of a 6-sided die is 3.5.
Given N, simulate 1e8 N-sided dice rolls by creating a vector of 1e8 uniformly distributed random integers. Return the difference between the mean of this vector and the mean of integers from 1 to N.
function dice_diff = loln(N)
A=randi([1,N],1e8,1)
M=mean(A)
B=1:N
m=mean(B)
dice_diff =abs(M-m);
end
Here is my code, but it can't work out as it needs too long time to creat A.
In problem 16 I used the following solution:
function b = nearZero(a)
b = max(a(imdilate(a == 0, [1 1 1])));
end
It is working pretty well on mathlab but when I submit my answer to cody, the following error is generated:
Undefined function 'imdilate' for input arguments of type 'double'.
Error in nearZero (line 2)
b = max(a(imdilate(a == 0, [1 1 1])));
Error in Test1 (line 3)
assert(isequal(nearZero(a),b))
In number 5, its written that the correct answer is c = 1 but the secomnd person has more change than the first person, therefor the correct answer should be 2.Likewise in number 6.
Hi, I'm trying to solve this problem but I'm getting an error so far.
Problem:
Given a vector a, find the number(s) that is/are repeated consecutively most often. For example, if you have
a = [1 2 2 2 1 3 2 1 4 5 1]
The answer would be 2, because it shows up three consecutive times
What I've written so far (not done):
a = [1 2 2 2 1 3 2 1 4 5 1];
[x,y] = size(a);
counter = zeros(1,10);
if x == 1
for i=1:1:y
if a(i) == a(i+1)
counter(a(i)) = counter(a(i))+1
end
end
else
for i=1:1:x
if a(i) == a(i+1)
counter(a(i)) = counter(a(i))+1
end
end
end
But it says "error" in the line of "if a(i) == a(i+1)". I noticed that it creates a variable called "i" which value is 11, but it should create a vector from 1 to 11. What's wrong here?
I know my solution might not be in the right direction or something, but please don't tell me anything!
Thanks in advance
Jan
Jan
Last activity 2024 年 10 月 4 日

Table of Matlab release features

After reading Rik's comment I looked for a list of Matlab releases and their corresponding features. Wiki: Matlab contains an exhaustive list, but what about having a lean version directly in the forum?
If this is useful, feel free to expand the list and to insert additions. Thank you.
Rik
Rik
Last activity 2022 年 11 月 4 日

How to create a GUI

There are multiple ways to create a graphical user interface (GUI) in Matlab. Which method is the best depends on multiple factors: the complexity of the project, to what extent it should be a long-term solution, on what releases your GUI should work, your available time, your skill level, and probably other factors I'm forgetting.
To keep the thread clear I'll attempt to provide a short outline a few ways in this question, and leave the details for the answers. (@anyone with editing privileges: feel free to update the section below if I missed something important and am slow in editing this question)
---------------------------------------------------------------------------------------------------
GUIDE
GUIDE is probably the first tool new users will encounter. It is very useful for quickly putting something together, but it is otherwise fairly limited. It requires maintaining (and distributing) both a .m and a .fig file. Note that the GUIDE environment will be removed in a future release. After GUIDE is removed, existing GUIDE apps will continue to run in Matlab but they will not be editable in GUIDE. If you're starting a new GUI, don't use GUIDE. If you're updating an existing GUIDE GUI, migrate it to AppDesigner. In R2021a the first step for this removal was taken: all templates except the blank template have been removed.
GUILT
Although I haven't had a detailed look myself, it seems a list like this is not complete without at least mentioning the GUI Layout Toolbox, which is available on the file exchange and offers a lot of customization options.
Programmatic GUIs
You can bypass GUIDE and use the normal figures and functions like uicontrol to build GUIs from code. This makes the design less visual, but more flexible for future additions.
App Designer
The official successor to GUIDE, AppDesigner is not based on functions, but works similar to a class. It uses uifigure and mostly uses graphical elements that are incompatible with 'normal' GUIs that are created with a figure (or .fig).
Dear Sir or Madam
I tried to solve the cody-problem namend in the title.
Could you pleas tell me how I should name the vektor/variable in which it should be presentet?
Thank you for helping me.
Yours faithfully
Jann Borlinghaus
Dear MATLAB community,
How can I help my close friend who's bad at math and programming learn MATLAB?
He's a final year chemical engineering student who struggles even to plot two functions on the same graph in his computational fluid dynamics class (there was no prereq for matlab skills).
In his first year, I saw him get dragged through the introductory engineering classes which was his first encounter with MATLAB. Students were taught a few rudimentary programming skills and then were expected to make a code for a 'simple' tic-tac-toe game. It took him hours of blank looks and tutoring to even understand the simplest of boolean operators. He was never able to write a working function without the supervision of a friend or tutor. Needless to say, he was permanently scarred by the experience and swore to avoid using it forever.
After 3 years of avoiding MATLAB, he realised how not knowing it hurt him during his final year project. He had to solve a system of pdes to model the performance of a reactor and practically speaking, MATLAB was the most suitable software at hand. He ended up having to get a friend to help him code the equations in while also having to oversimplify his model.
The weird thing is that: most students from his chemical engineering faculty were not expected or encouraged to use MATLAB, almost all of their prior assignments required no use of MATLAB except that infamous first year course, and most of his peers also avoided using MATLAB and resorted to Excel. It is my understanding that Excel cannot match MATLAB's efficiency and clarity when solving calculus problems so it was not uncommon to see extremely long Excel spreadsheets.
Anyway, my friend is, with the help of a friend's past year MATLAB codes, trying to finish up his computational fluid dynamics assignment that's due soon. He finishes university in 2 weeks time.
Even though he knows that not every engineer has to use MATLAB in the workplace, he somehow wishes he was able to learn MATLAB at his glacial pace. I find it such a pity that he was never able to keep up with the pace of learning that was expected which begs the question: are students who are too slow at learning programming better of in a different field of study?
If you've managed to read to the end of this, thank you so much. I just don't know how to help my friend and I'm hoping some of you might be able to suggest how I can help him be better at it. I believe he has potential but needs special help when it comes to MATLAB.
All helpful and constructive suggestions considered,
Thank You All
I wrote a Cody problem, but I want to prevent people from using tricks to get a false "best" solution.
For example, many people do something like the following:
regexp '' '(?@"CODE HERE)';
in order to get the size of their program down to something quite small. I want to prevent this. I have seen people using some weird tests to try to block this, but I don't know how they work and when I try to copy them they fail.