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Gregory
Gregory
Last activity am 13 Jun. 2017

Matlab webread (or urlread) Cody

Something seems to either have changed with webread/urlread behavior with R2016a or the Cody site has changed its authentication after it's September 2016 upgrade. Now, when ever I make a call using either webread (with weboptions) urlread using "My Cody" url, I get the html that corresponds to an unauthenticated user.
Ex: https://www.mathworks.com/matlabcentral/cody/players/1261697-gregory/solved
I've tried passing credentials using weboption and also cached the credentials using the built in Matlab browser - neither helped in seeing the authenticated version of this page.
Any help in understanding where the problem/solution lies would be helpful. Easily reproduced by running...
URL = 'https://www.mathworks.com/matlabcentral/cody/players/1261697-gregory/solved';
[Contents Status] = urlread(URL);
Compare this to the source pulled down when authenticated with Chrome (for example, search for the work "two"). FYI: this has worked for a couple of years up until now...
Matt Tearle
Matt Tearle
Last activity am 6 Mär. 2023

MATLAB poems -- let's hear 'em!

Inspired by Chad Greene's " MATLAB jokes or puns " thread, and in celebration of 15 years of the MathWorks Community site, does anyone out there want to share their poetic creativity? Limericks, haiku, sonnets... Go!
And to start off, my (slightly off-topic) submission on Chad's thread:
There was an old math guy called Cleve
who, while teaching, a pipe-dream conceived:
of a language so clean
you can say what you mean!
From our suffering we've all been relieved.
O45
O45
Last activity am 23 Okt. 2018

Best solution to cody problems

Hi, I am uploading the answers to cody problems. Although most of answers are correct but my size is bigger than the best answer. How can I view the best answer?
The community is very helpful, yet I feel really powerless that I cannot find the appropriate way to code, nor find the problems with the codes I have written. I have read numerous books on MATLAB, mostly related with science and engineering applications. Any advice to improve would be greatly appreciated. Thanks.
James
James
Last activity am 11 Jun. 2015

Issue with Cody Challenge Badges?

Apologies for putting this question here, but I'm not sure there's a specific forum for Cody-related questions.

I recently noticed that a new badge for "Magic Numbers Master" had been created and awarded. When I entered my profile to check that out, I noticed that I had received that badge, but lost the badge for "Cody Challenge Master." I thought that maybe my solution had been messed up because of a change in one of the test suites that my solution missed, as this has happened a number of times on other problems. According to the text underneath the badge icon, I've still solved all 96 of the questions in the Cody Challenge. All of the problems listed as part of that challenge are still marked as "Solved." Has anyone else run into this issue?

Chad Greene
Chad Greene
Last activity am 12 Sep. 2023

Matlab jokes or puns

Are there any good Matlab jokes? I don't mean why or any other Easter eggs, I mean good jokes involving Matlab. Actually, that bar may be a bit too high. Any jokes, good or bad, let's hear 'em.
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
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
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
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~~~
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?
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
What do you think of Cody? I'm interested in your comments
Raviteja
Raviteja
Last activity am 27 Jan. 2012

Good programming practice...

Hello all,
Please explain good MATLAB programming practice methods. It will help to the guys who are new to programming like me.
Previously I used
for i=1:10
after following some suggestions from this answers pages I learnt to use
for i1=1:100
This is the good way to write programs.
Like this, as a professional programmer, please mention some good programming practice techniques.
It will useful to all!
Capital letters are obtained by capitalizing the LaTeX command for the lowercase version. Capital letters in grey are exceptions which have no LaTeX commands. For example, to produce a capital chi simply type X (this also applies for the lowercase omicron).
When two versions of the lowercase letter are available, a var prefix can be added to obtain the second version. For example, the two versions of epsilon are \epsilon and \varepsilon.
--------------------------------------------------------------------------------------------------------------------------------------------------------
The code used to generate the table:
greeks = ...
{'ALPHA' 'A' '\alpha'
'BETA' 'B' '\beta'
'GAMMA' '\Gamma' '\gamma'
'DELTA' '\Delta' '\delta'
'EPSILON' 'E' {'\epsilon','\varepsilon'}
'ZETA' 'Z' '\zeta'
'ETA' 'H' '\eta'
'THETA' '\Theta' {'\theta','\vartheta'}
'IOTA' 'I' '\iota'
'KAPPA' 'K' '\kappa'
'LAMBDA' '\Lambda' '\lambda'
'MU' 'M' '\mu'
'NU' 'N' '\nu'
'XI' '\Xi' '\xi'
'OMICRON' 'O' 'o'
'PI' '\Pi' {'\pi','\varpi'}
'RHO' 'P' {'\rho','\varrho'}
'SIGMA' '\Sigma' {'\sigma','\varsigma'}
'TAU' 'T' '\tau'
'UPSILON' '\Upsilon' '\upsilon'
'PHI' '\Phi' {'\phi','\varphi'}
'CHI' 'X' '\chi'
'PSI' '\Psi' '\psi'
'OMEGA' '\Omega' '\omega'};
h = figure('units','pixels','pos',[300,100,620,620],'Color','w');
axes('units','pixels','pos',[10,10,600,600],'Xcol','w','Ycol','w',...
'Xtick',[],'Ytick',[],'Xlim',[0 6],'Ylim',[0,4]);
% Loop by column and row
for r = 1:4
for c = 1:6
el = (r-1)*6 + c;
% Title
text(c-0.5,5-r,greeks{el,1},'Fonts',14,'FontN','FixedWidth',...
'Hor','center','Ver','cap')
% Color cap latter in grey or black
if strcmp(greeks{el,2}(1),'\')
clr = [0, 0, 0];
else
clr = [0.65, 0.65, 0.65];
end
% Cap letter
text(c-0.5,4.87-r,['$\rm{' greeks{el,2} '}$'],'Fonts',40,...
'Hor','center','Ver','cap','Interp','Latex','Color',clr)
% Lowercase letter/s (if two variants)
if iscell(greeks{el,3})
text(c-0.75,4.48-r,['$' greeks{el,3}{1} '$'],'Fonts',20,...
'Hor','center','Interp','Latex')
text(c-0.25,4.48-r,['$' greeks{el,3}{2} '$'],'Fonts',20,...
'Hor','center','Interp','Latex')
% Latex command
text(c-0.5,4.3-r,['\' greeks{el,3}{1}],'Fonts',12,'FontN','FixedWidth',...
'Hor','center','Ver','base')
else
text(c-0.5,4.48-r,['$' greeks{el,3} '$'],'Fonts',20,...
'Hor','center','Interp','Latex')
text(c-0.5,4.3-r,['\' greeks{el,3}],'Fonts',12,'FontN','FixedWidth',...
'Hor','center','Ver','base')
end
end
end
% Print to pdf
export_fig greeks.pdf
The link to export_fig.
And here is the link to the pdf on scribd: http://www.scribd.com/doc/159011120/Greek-alphabet-in-latex