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Ken Atwell


MathWorks

356 total contributions since 2011

Former product manager for MATLAB, but the company decided to trust me with the source code, so now I'm a developer.

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Matrix indexing with two vectors of indices
Given a matrix M and two index vectors a and b, return a row vector x where x(i) = M(a(i),b(i)).

1 year ago

Solved


Getting logical indexes
This is a basic MATLAB operation. It is for instructional purposes. --- Logical indexing works like this. thresh = 4...

1 year ago

Solved


Return elements unique to either input
Given two numeric inputs a and b, return a row vector that contains the numbers found in only a or only b, but not both. For ex...

1 year ago

Solved


Set the array elements whose value is 13 to 0
Input A either an array or a vector (which can be empty) Output B will be the same size as A . All elements of A equal to 13...

1 year ago

Solved


Replicate elements in vectors
Replicate each element of a row vector (with NaN) a constant number of times. Examples : n=2, A=[1 2 3] -> [1 1 2 2 3 3] n=0...

1 year ago

Solved


Find the largest value in the 3D matrix
Given a 3D matrix A, find the largest value. Example >> A = 1:9; >> A = reshape(A,[3 1 3]); >> islargest(A) a...

1 year ago

Solved


Check if number exists in vector
Return 1 if number _a_ exists in vector _b_ otherwise return 0. a = 3; b = [1,2,4]; Returns 0. a = 3; b = [1,...

1 year ago

Answered
Why can't I mex cpp with matlab?
MEX is working as expected. How old is this code? Xcode's compiler is alerting you to several risky programming patterns bei...

1 year ago | 1

Answered
Does anyone know how to run selection on mac?
Shift+F7. If you are on a lap, depending on your system preferences, you might need to add Fn to that chord (I do). As Jan sug...

2 years ago | 1

Answered
Why did I get this error?
The function |deg2rag| was introduced in R2015b, according to the <http://www.mathworks.com/help/matlab/ref/deg2rad.html documen...

2 years ago | 0

Answered
OS X 10.5.8 install
R2010b was the last release to support OS X 10.8: <http://www.mathworks.com/support/sysreq/release2010b/macintosh.html>

2 years ago | 0

Answered
multiple line edit is not allowed on MATLAB file editor window?
The MATLAB Editor does not have this, I think. Do you have an example MATLAB source file you can share with us where this kind ...

2 years ago | 0

Answered
Question on using a while loop?
To add the bet from the total, use: Bank = Bank + Bet; Subtraction will be similar, using "-" of course. To get your p...

2 years ago | 0

Answered
Does matlab become slow and unusable when working in a folder with many files?
When you cd into a folder with 50,000 file, bear in mind that *all of these files are visible from MATLAB path*, and therefore m...

2 years ago | 1

Answered
Can anyone help me with telling me how my variable is undefined?
You are writing a function that accepts 'temperature' as an input parameter. So, 'temperature' will exist inside your functions...

2 years ago | 0

Answered
Applying multiple conditions to an 'if' statement
You might be looking for <http://www.mathworks.com/help/matlab/ref/logicaloperatorsshortcircuit.html logical operators>.

2 years ago | 0

Answered
Mex can't find compiler after Xcode 7 update (R2015b)
*EDIT* MathWorks has produced a patch for this issue. If at all possible, use the procedure outlined at http://www.mathworks.co...

2 years ago | 16

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Answered
Print out values in a while loop each time into an array.
A semicolon at the end of the line suppresses output [ <http://www.mathworks.com/help/matlab/matlab_prog/symbol-reference.html#b...

2 years ago | 0

Answered
32 bit mex file not working in a 64 bit version of matlab
This is a stab in the dark, but a Google search found <https://github.com/filipjares/tdv/tree/master/src/gcs/private this on Git...

2 years ago | 2

Answered
Tranform Python code in Matlab
MATLAB is 1-indexed, so I think you're looking for something like: diff = X(pairs(:,1),:) - X(pairs(:,2),:);

2 years ago | 0

Answered
Read in file that has raw binary image data and an XML footer
You've got the right idea. Since you know the size of the image, open the mixed image/XML file with <http://www.mathworks.com...

2 years ago | 0

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Answered
how to select a number randomly from a series of fixed number
>> a(randi(numel(a))) In other words, pick a random (integer) number _N_ between 1 and the number of elements in "a", then r...

2 years ago | 0

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Answered
Why can parfor only write to one dimension?
From parfor's perspective, "result" is being accessed randomly. Try this instead: parfor i=index results1{i} = an...

2 years ago | 0

Answered
How to do better commenting in Matlab script?
You'll get to the settings you need under "Home -> Preferences -> Editor/Debugger -> Display" and "Home -> Preferences -> Editor...

2 years ago | 0

Answered
Generating a mex file from .m file
It looks like your system does not have the GNU C++ standard library installed. I believe this can be the case in some down dis...

2 years ago | 0

Answered
How can I setup MATLAB to differentiate things like recent directories and command histories for two unrelated projects?
I don't think there is direct support for like this you describe. Path management can be semi-automated with scripts, but comma...

2 years ago | 0

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Answered
Bug in matlab 2013b: all windows resize (get very small) when I right click in the Editor. It returns to normal only when program is restarted.
See <http://www.mathworks.com/matlabcentral/answers/122347-matlab-editor-windows-and-fonts-resize-get-smaller-on-right-click-why...

3 years ago | 0

Answered
Why Matlab window gets smaller pressing right mouse button?
See <http://www.mathworks.com/matlabcentral/answers/122347-matlab-editor-windows-and-fonts-resize-get-smaller-on-right-click-why...

3 years ago | 0

Answered
parallel computing speed question when the body of the parfor loop takes about 2 seconds
It really depends on what "dosomething" is doing. If it is pure computation, it should be a big win. If there is file or netwo...

3 years ago | 0

| accepted

Answered
How to selectively import a column from a text file containing lot of headers
You can import all 57 columns with the following: txt=fileread('1.TXT'); % Read 57 numeric columns of data textscan(txt,...

3 years ago | 1

| accepted

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