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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 il 27 Maggio 2021

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 il 28 Feb 2021

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
Is anyone else disappointed with uifigures? It seems apparent that these will eventually replace traditional figures, but there is still so much that doesn't quite work. I've tinkered with uifigures since their introduction in release 2016a, but even in 2020a I can't reliably export a uifigure to a graphics file. Sure it works sometimes, but not if a uipanel is present. The exportgraphics command is not as powerful as the print command, leaving some graphic formats (such as *.svg and *.eps) unsupported. How do you generate graphic files of a specific size? You can't even use subplots without overriding the default AutoResizeChildren setting!
Everything with uifigures seems to be slower and less stable than the figure variant. App Designer is much better than GUIDE, but that is not exactly high praise. I would rather generate "apps" programatically across several files instead of dealing with a single-file class definition containing 1000+ lines.
Where is this transition going? MATLAB graphics are moving away from Java in favor of JavaScript, and I'm not sure that we are at all ready for that.
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
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
Meta threads have a tendency to grow large. This has happened several times before (the wishlist threads #1 #2 #3 #4 #5, and 'What frustrates you about MATLAB?' #1 and #2).
No wonder that a thread from early 2011 has also kept growing. After just under a decade there are (at time of writing) 119 answers, making the page slow to load and navigate (especially on mobile). So after a friendly nudge; here is a new thread for the things that are missing from Matlab.
Same question: are there things you think should be possible in Matlab, but aren't? What things are possible with software packages similar to Matlab that Matlab would benefit from? (note that you can also submit an enhancement request through support, although I suspect they will be monitoring activity on this thread as well)
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)
Rik
Rik
Last activity il 17 Set 2024

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 il 23 Lug 2023

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 il 4 Ott 2024

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 il 4 Nov 2022

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).
This is the 5th installment of the wish-list and bug report thread.
This topic is the follow on to the first Wish-list for MATLAB Answer sections and second MATLAB Answers Wish-list #2 (and bug reports). The third started out as New design of the forum - grey on white and the fourth MATLAB Answers Wish-list #4 (and bug reports) is also growing so large it is slow to load and navigate.
Same idea as the previous ones: one wish (or bug report) per answer, so that people can vote their wishes.
What should you post where?
Wishlist threads (#1 #2 #3 #4 #5 #6): 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)
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.