Matt J

Last seen: Today

7,662 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
Boolean operation of A not B
c=setdiff(b,a)

4 hours ago | 1

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Answered
Find values that put equation to zero
gamma=nan(T,1); j=1; %increment level. The loop will work for j>1 as well. for i=1:j:T; ci=C(i); si=S(i); mi=M(i); ...

12 hours ago | 0

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Answered
Fzero question : Error using fzero (line 308) Initial function value must be finite and real.
Well you have divisions by x in your function, so naturally choosing x0=0 will not give you a finite initial value. Also, you a...

14 hours ago | 0

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Answered
find the object closest to the center
I found it highly challenging to close the blobs surgically enough so that the two lungs and the bed are always guaranteed to fo...

1 day ago | 1

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How to implement triple summation?
Well, for each fixed p and q, the inner sum over m is just a discrete convolution. So, perhaps the best solution is to do a doub...

1 day ago | 0

Answered
how to use binary morphological operations for corner detection
I don't think you can, but if the shape is convex, you can use this FEX tool instead, https://www.mathworks.com/matlabcentral/f...

1 day ago | 1

Answered
How to calculate the camera intrinsics K , rotation matrix R and translation vector T through the camera projection matrix?
For various randomized input matrices, it gives the same output (within numerical precision) as my own decomposition routine (at...

1 day ago | 0

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Answered
How to decompose the "camera projection matrix" into camera internal and external parameters?
If you have the 3x4 camera projection matrix already, then it can be directly decomposed into intrinsics and extrinsics. The att...

1 day ago | 0

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Answered
How do I find the line representing the intersection of two planes?
HINT: You can get the normals to the planes using cross() % Plane 1 A = [1 1 1]; B = [2 -3 5]; C = [-7 2 1]; % Plane 2 D =...

1 day ago | 0

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Answered
Using matfile to partially extra data still loads entire file into memory
We can run a test right here. The one below suggests there is some benefit, though perhaps not as much benefit as I would have e...

2 days ago | 0

Answered
How can I find the eigenvalues of an n-by-n matrix using For Loops?
What I do have available to me is a previous code I wrote that would solve any n x n matrix using Gauss-Jordan elimination but t...

2 days ago | 0

Answered
changing variable names when saving variables
What I want is that, when I open the variables I want it to call them a different name for every subscript. Now the variable is ...

2 days ago | 0

Answered
Mean, Max and Min of Structured Cell array
You should first convert everything to table form. Column3={{'dog';'dog';'dog'},{'cat';'cat'}}; %Original data Column4={[1;2;...

2 days ago | 1

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Answered
Is it possible to write methods that iteratively process each element of an objectarray without writing for-loops each time?
It is not possible in a get.property() method, but it is possible in a normal method. function meanValues = mean(Objects) ...

2 days ago | 0

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Answered
Sum of a portion of 3D matrix elements
[I,J,K]=ndgrid(1:N); total = sum(A(I<=J & J<=K))

2 days ago | 0

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Answered
'drawcircle' and 'roi.cricle' do not respect preset Radius
I think you need to specify the center coordinate as well.

2 days ago | 0

Answered
How do I delete slices in 3D-Array?
Saravanan Sengottuvel's answer moved here: Generating an example 3D array that has 10 slices A = repmat([0 0 0 0; 1 0 0 0; 1 0...

2 days ago | 0

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Answered
Calculating a matrix with a specific form
Another solution, using func2mat (Download). N=size(x,2); C=func2mat( @(m)cross(repelem(m,1,N),x) , ones(3,1) , 'doSparse',0...

3 days ago | 0

Answered
Simultaneously interpolating over multiple rows of a matrix.
This might be better, e=1:K; F=griddedInterpolant(mat(ind1,:),{e,grid}); vals_temp = F(e,qvec);

3 days ago | 0

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Answered
Simultaneously interpolating over multiple rows of a matrix.
V=mat.'; vals_temp = interp1(grid,V(:,ind1),qvec);

3 days ago | 0

Answered
How to find the first number, ignore subsequent until a greater number repeats.
Is this what you want? A = [ 0 3 0 3 0 3 0 3 0 4 0 4 0 4 0 4 0 5 0 5 0 5 0 5 0 5 0 3 0 3 0 3]; cA=cummax(A); b1=find(A==3...

3 days ago | 1

Answered
Removing lines in matrix
Hint: do something with this line: ind = any( A==0 | abs(A)==10 ,2)

4 days ago | 1

Answered
Matlab clears persistent and global variables in fmincon when activating UseParallel
This happens because, in parallel computing, it isn't easily definable what it means for a variable to "persist". A peristent va...

4 days ago | 2

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Answered
How to add a legend to all open figures?
For example, %% Open several figures with subplots for i=1:2 figure(i) for j=1:2 subplot(2,1,j) ...

4 days ago | 0

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Answered
How can i plot multiple objects in same 3D space i.e. plot3 ?
Using hold on and hold off, you can add anything you want to a pre-existing 3D axis, even the results of a 2D plotting command. ...

4 days ago | 0

Answered
How to use fmincon with vectors? (error message: not enough input arguments)
fun = @(x) -100*(x(1,:)-x(2,:).^2).^2 + (test-x(1,:)).^2;

5 days ago | 0

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Answered
Hessian output using simulannealbnd and fmincon
I'm assuming you can't simply do an analytical Hessian computation at the solution you found... One alternative would be to run...

5 days ago | 0

Answered
fsolve with multiple tolerance levels
You can use fmincon (instead of fsolve) to formulate the tolerances as nonlinear inequality constraints. Or you can use lsqnonli...

5 days ago | 0

Answered
Elliptical trajectory and plot waypoints for robotic arm simulation
Fairly easy to do with this FEX submission, https://www.mathworks.com/matlabcentral/fileexchange/87584-object-oriented-tools-fo...

5 days ago | 0

Answered
Creating random non-discrete values and assigning weights
As an example, weightList=[0.4 , 0.1, 0.3, 0.2]; x=rand(1,6)*40, Weights = weightList(discretize(x,0:10:40))

5 days ago | 0