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Andrew Newell
Andrew Newell
Last activity 2017 年 4 月 23 日

Why doesn't Cody accept a class definition?

I created a solution for Cody Problem 1745 (Get me!) that is very simple and works perfectly on my computer; but in Cody, it results in the error:
Error: Undefined function or variable 'me'.
The test code is:
get = me();
y = rand(1,12345);
!rm now.m
!rm assert.m
assert(get == now)
My solution is:
classdef me
methods
function tf = eq(obj,~)
tf = true;
end
end
end
Why doesn't Cody accept this?
(P. S.) And why doesn't it accept function definitions like
function justDoIt
(which are appropriate for some problems and accepted by MATLAB) but requires at least one input and output?
if i want write fewer codes in cody,what should I pay attention to?
Can anyone explain how Cody calculates the size of a program?
I read the help, but couldn't understand. :(
Why cody does not allow 'eval', 'evalc','feval' etc functions in the solutions? What is alternative to these functions?
e.g. I need to use:
if f='3*x'
x=0:10;
y=eval(vectorise(f))
so that values of y can be calculated as 3.*x
bt cody does not let us to use functions like eval
What is the alternative?
I have been stuck in the Cody question: Problem 31. Remove all the words that end with "ain"
http://www.mathworks.com/matlabcentral/cody/problems/31-remove-all-the-words-that-end-with-ain
for the whole afternoon. My codes below passed the first two tests but failed in the third one, because my codes cannot separate "" and ain. Anyone could help?
function s2 = remAin(s1)
s1_cell = strread(s1, '%s');
[s1_cell{find(not(cellfun('isempty', regexp(s1_cell, '\w*ain\>'))) == 1)}] = deal(' ');
s2 = strjoin(s1_cell');
s2 = strrep(s2, sprintf('%c%c%c', 32,32,32), sprintf('%c%c', 32,32));
if s2(end) == ' ' && s2(end-1) == ' '
s2(end) = [];
end
end
Sven
Sven
Last activity 2023 年 7 月 7 日

What's on your personal MATLAB to-do list?

What MATLAB tools or functions have you been thinking about making but haven't quite gotten around to it?
It can be something specific to your work if you'd like, but it's preferably:
  • the kind of tool or task that we don't really expect in the next MATLAB release (ie., not a frequent entry in a MATLAB wishlist)
  • something that would be useful to you and (hopefully) others if it existed.
  • something that could conceivably be made by people(s) in the user community
Think of it maybe as a file exchange wishlist.
Votes for good ideas . I guess you'll get more votes if it's an idea others want to see made as well.
Probably no single accepted answer, but it would be nice to see what people have thought about and maybe we can bring a few ideas to fruition (or find that someone's already done it)
For example:
  • I've been wanting to write an object-oriented replacement for the NURBS toolbox which is a great toolbox but is very unwieldy to use.
Salam,
While I was playing with Cody, I found one interesting question that asked to write MATLAB function to create times-table (can be found here: http://bit.ly/1cWZGGM ). The question itself was easy, but I had problems to figure out how could someone solve this problem with compact code of size 10 !!
After I've checked the leading answer, it seems to be written in Chinese not in MATLAB :)
Here is the answer:
function m = timestables(n)
regexp '' '(?@A=repmat([1:n]'',1,n);m=A.*A'';)'
end
Could anyone translate this to me so that I can use it in my future attempts ? :P
Regards.
In a previous Q & A, Jan Simon pointed to Cody: Sum 1:2^n. The current leading solution to that problem has node-count (or more simply, "length") 10. Apparently, 10 is the minimal length (per the official length-function on File Exchange) of any function taking input & generating output:
function y = test_cody_solution(x)
y = x;
end
Per Cody instruction examples, additional computation within a function definition increases the solution length. For example, both of the following functions have length 12:
function y = test_cody_solution(x)
y = [x];
end
function y = test_cody_solution(x)
y = x+1;
end
My question is: what kinds of ninja-style coding idioms even exist in MATLAB which actually perform definite computation but at the same time do not increase the node-count above 10? I'm not able to imagine what could be going on in order for someone to solve a given non-trivial Cody puzzle in length 10 or 11? IOW, without respect to any particular Cody problem, could someone please give an example of a non-trivial function which somehow comes in at or just above the absolute lower bound? Any explanation of the magic would be appreciated as well.
Thanks, Brad
ricardo gunawan
ricardo gunawan
Last activity 2013 年 7 月 15 日

Problem 9. Who Has the Most Change?

function b = most_change(a)
a(:,1)=a(:,1)*0.25;
a(:,2)=a(:,2)*0.1;
a(:,3)=a(:,3)*0.05;
a(:,4)=a(:,4)*0.01;
d=sum(a,2);
c=max(d);
for i=1:length(d)
if d(i)==c
b=i;
end
end
i got wa please explain idont understand
Oleg Komarov
Oleg Komarov
Last activity 2023 年 7 月 27 日

Spellcheck functionality in MATLAB editor

I would like to receive your feedback:
  • would you find useful to have spellcheck built into the MATLAB Editor?
(Consider also an associated toggle, positioned somewhere in the Editor, that would enable/disable the spellcheck for selective use)
Lately, I am writing many quick analyses for publish() and I find that first publishing to MS Word (to check the spelling) and then re-publishing to .html, after manual corrections, disrupts the working.
IMHO, the idea to include spellcheck into the editor would be consistent with the renewed visibility of the PUBLISH tab.
Given a tic tac toe board:
1 represents X
0 represents empty.
-1 represents O
It is X's move. If there is an immediate win possibility, choose a square for an immediate win. Otherwise return 0.
Return absolute index of the square of choice. If multiple square are valid, return them in order.
Example:
Input a = [ 1 0 1
-1 1 0
0 -1 -1]
Output wins is [4 8]
Can anyone explain it in detail?
I'm confused with the sentence I marked ans bold style.
Thanks a lot~~~
Cris Luengo
Cris Luengo
Last activity 2012 年 8 月 14 日

Unlocking answers to last Cody problem?

I've written a valid answer to the last Cody problem, but it is not even close to the best answer. I have no idea how they made this short answer. To unlock it I need to solve another Cody question, but there are none left... :(
Anybody know how to unlock the last question?
Marco Castelli
Marco Castelli
Last activity 2020 年 6 月 9 日

Cody: Problem 30 - function Sortrows

Hi,
i'm "solving" number 30 cody's problem.
I think to solve that whit sortrows function.
If I have a z vector:
j = sqrt(-1);
z = [-4 6 3+4*j 1+j 0];
my funtion is:
function z = complexSort(z)
z(2,:)=sqrt(real(z).^2+imag(z).^2);
z=sortrows(z',-2);
z=z(:,1);
end
End it return the result
z =
6.0000 6.0000
3.0000 - 4.0000i 5.0000
-4.0000 4.0000
1.0000 - 1.0000i 1.4142
0 0
The question is: why imagine part in input is positive e sortrows trasform it in negative?
best regards
Marco
NOTE: this discussion is continued at MATLAB Answers Wish-list #6 (and bug reports)
This topic is for features you would like to see for the MATLAB Answers facility itself, and also for bug reports about the MATLAB Answers facility.
This topic is the follow on to the earlier Wish-list for MATLAB Answer sections. That topic grew large enough to become unwieldy; and Mathworks has made enough changes to make a number of the past points no longer of relevance. There was also a more limited purpose <http://uk.mathworks.com/matlabcentral/answers/216662-new-design-of-the-forum-grey-on-white-wish-list-3-bug-reports
I suggest one wish (or bug report) per answer, so that people can vote their wishes.
What do you think of Cody? I'm interested in your comments
Walter Roberson
Walter Roberson
Last activity 2022 年 7 月 14 日

MATLAB in unexpected places

This topic is for unexpected or bizarre or humorous references to MATLAB. Specific citations would be appreciated.
Paulo Silva
Paulo Silva
Last activity 2024 年 5 月 10 日

What matlab easter eggs do you know?

Please post the easter eggs that you have found so far if they aren't already posted by someone else.
Let's try to make a good Matlab easter egg list because it seems that there isn't one.
What should be posted:
  • Unexpected but intentional behaviour
  • Special things that the programmers left for us to discover
  • Extra code inside a function that can be used for other purposes
  • Hidden pictures and audio clips
What shouldn't be posted:
  • Repeated Easter Eggs, if someone already posted it please don't repeat
  • Bugs in functions that cause trouble and might be fixed in later versions
  • Matlab games that come with the program unless they aren't mentioned in the documentation (the games are in the other demos, try the xpbombs and fifteen, you can even see the code for both games)
Paulo Silva
Paulo Silva
Last activity 2023 年 8 月 14 日

What is missing from MATLAB?

I'm curious, is there something you wish to do with MATLAB but you can't, maybe something you can do with other similar software but can't with MATLAB?
For new entries, please use the follow-up thread here. Please do not post new answers in this thread.
This topic (which was not started by Mathworks) is for features you would like to see for this MATLAB Answers facility.
I suggest one wish per answer, so that people can vote for individual 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)