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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
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~~~
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
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
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
[INDEX]
--------------------------------------------------------------------------------------------------------------------------------------
[MOTIVATION]
Why should we use markups in the body of our questions?
The answer is a question: which of the two versions is more likely to be understood in a glimpse and has more chances to be answered by our readers?
.
< Consider the following question >
I have a vector of weights W=[10,20,30,50,23434,1,2.4,2] and a matrix A=rand(100,8) and I would like to find the row-wise weighted sum of A. I am proceeding in the following way: B=zeros(size(A)); for c=1:numel(W) B(:,c)=A(:,c)*W(c); end B=sum(B,2); Somehow I get huge numbers can you please help?
.
< Now, consider its formatted version >
I have a vector of weights W = [10,20,30,50,23434,1,2.4,2] and a matrix A = rand(100,8) and I would like to find the row-wise weighted sum of A.
I am proceeding in the following way:
B = zeros(size(A));
for c = 1:numel(W)
B(:,c) = A(:,c)*W(c);
end
B = sum(B,2);
Somehow I get huge numbers can you please help?
--------------------------------------------------------------------------------------------------------------------------------------
[AKNOWLEDGMENTS]
In alphabetical order by nickname, thanks for their suggestions to:
Walter Roberson
--------------------------------------------------------------------------------------------------------------------------------------
[LOG]
  • 06 Aug 2011, 13:17 BST - created and added boldface.gif
  • 06 Aug 2011, 14:59 BST - added italic.gif
  • 06 Aug 2011, 18:58 BST - added index section
  • 07 Aug 2011, 00:03 BST - added code.gif and tutorial series section
  • 07 Aug 2011, 01:50 BST - added monospaced.gif, numlist.gif, bullist.gif and hyperlink.gif
  • 13 Aug 2011, 14:27 BST - added motivation section
  • 18 Aug 2011, 01:44 BST - added aknowledgments section and link to wish-list
--------------------------------------------------------------------------------------------------------------------------------------
[TUTORIAL Series]
Do not forget to read the Markup help (located on the top-right corner of the Body pane)
Vote on Wish-list for MATLAB Answer sections my post if you think that a tutorial section on top of Answers could be useful.
Jason
Jason
Last activity am 16 Dez. 2020

Best way(s) to master MATLAB?

Now, I am still a novice when it comes to programming. I believe MATLAB is definitely a great programming tool, one that I can play with, particularly, when I have free time.
I would love to hear from all answerers, what are the ways that can make one proficient in this field?
Walter Roberson
Walter Roberson
Last activity am 14 Jul. 2022

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 am 10 Mai 2024

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 am 14 Aug. 2023

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.
amit jain
amit jain
Last activity am 2 Jun. 2023

How to learn MATLAB

What is the best way to learn MATLAB at home without a tutor?
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)