Matt J

Last seen: Today

8,039 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

PLEASE NOTE: I do not read email sent through my author page. Please post questions about FEX submissions in their respective Comments section.

Contact

Matt J's Badges

View details...

Answered
Efficient algorithm to compute only the most probable sequences of a random variable out of all possible sequences
This might work: p=[0.01 0.04 0.95]; S = most_probable_sequences(p, 2, 0.99) check=sum(prod(p(S),2)) %cumulative probabilit...

3 hours ago | 1

Answered
Skip the optimised parameters result if the objective function fails
Most optimization solvers have an OuputFcn option that will let you define your own stopping criteria: https://www.mathworks.co...

14 hours ago | 0

Answered
Dot indexing is not supported for variables of this type.
In line 18, you clearly epect FileList to be a structure variable, but it isn't. You should check what it actually is.

16 hours ago | 0

Answered
How to temporarily pause execution of a function for troubleshooting
You can set conditional breakpoints, https://www.mathworks.com/help/matlab/matlab_prog/set-breakpoints.html#buvvmfu-1

16 hours ago | 2

Answered
Graph a plane spanned by 2 vectors
You can use the planarFit class methods from this File Exchange submission. https://www.mathworks.com/matlabcentral/fileexchang...

16 hours ago | 0

Answered
Move the editor toolbar buttons to the right hand side
I raised this as a suggestion at the recent MAB. Since the panelists didn't mention that it was already possible, I'm going to a...

2 days ago | 0

| accepted

Answered
On my Matlab Desktop UI is a minimize/maximize toggle button. I want minimization/maximization to occur only when I press this button.
I raised this as a suggestion at the recent MAB. Since the panelists didn't mention that it was already possible, I'm going to a...

2 days ago | 0

| accepted

Answered
Creating a binary Matrix from X and Y Coordinates
As long as X and Y are matrix indices, you can do matrix=accumarray([X(:),Y(:)],1,targetSize); where targetSize is the desired...

2 days ago | 0

Answered
How to ask to user if to run or not a part of code?
For example, if inputdlg('Proceed? [Y/N]')=="N" break end There is also uiconfirm, https://www.mathworks.com/help/matlab/r...

3 days ago | 0

| accepted

Question

Shouldn't bwconvhull() be idempotent?
Shouldn't the following two calculations give the same results? load BWimage A=bwconvhull(BW); B=bwconvhull(bwconvhull(BW));...

3 days ago | 1 answer | 1

1

answer

Answered
circle through 3 points equation
You can use circularFit() from this File Exchange submission https://www.mathworks.com/matlabcentral/fileexchange/87584-object-...

3 days ago | 0

Answered
How to solve this simple matricial system?
u=A\(h*G)

3 days ago | 0

| accepted

Answered
Verifying an Vector composition
issorted(A(1:ceil(end/2))) & all(A==flip(A))

3 days ago | 1

| accepted

Answered
how do I select only the segmented region from a original image in MATLAB
You could do, S=regionprops(rgb_label,img,'Image')

3 days ago | 0

Answered
Jacobian of a state matrix over time using jacobianest
I don't think there is anything sub-optimal about the way you're using jacobianest now. In fact, by keeping the loop external to...

3 days ago | 0

Answered
Draw a gradient circle within a circle
One way might be to use a patch with vertex interpolation, as in this example. https://www.mathworks.com/help/matlab/ref/patch....

4 days ago | 1

| accepted

Answered
How to extrapolate a level curve form a 3D plot of a 2-variables function?
Youc an just use contour(). contour(Mach,Alfa,CM_plot,0);

4 days ago | 0

| accepted

Answered
Find very small zeros of a polynomial
It would be easier, both numerically and analytically, if you made the change of variables z=-(0.5/r)^6 and find the roots of th...

4 days ago | 0

| accepted

Answered
How can I register (merge) two images using homography matrix?
I'd recommend using fitgeotrans() rather than an unnormalized DLT approach. https://www.mathworks.com/help/images/ref/fitgeotra...

5 days ago | 0

Submitted

Object-oriented tools for fitting conics and quadrics
A tool set for fitting various conics and quadric surfaces, e.g., ellipses, cylinders, spheres, planes, cones, and lines.

5 days ago | 22 downloads |

Answered
How to plot 3d plane of type where one variable is missing like x + y = 0.....
If you mean that you have a plane equation of the form a*x+b*y+0*z=d, then you can use https://www.mathworks.com/matlabcentral/...

5 days ago | 0

| accepted

Answered
Array division of two non-zero arrays returns zero
W = double(Y(:))./double(X(:).');

5 days ago | 0

| accepted

Answered
parfeval inside a class method does not update a class property
Couldn't you do something like this? function execute(self, N) gd=gpuDevice; ...

6 days ago | 0

Answered
Subset and nanmean of a three dimensional array to a have a 2d array 1xndim
pt_lev8=reshape(pt_lev8,[],348); final = mean(pt_lev8(s1pos,:),1,'omitnan')

6 days ago | 0

| accepted

Answered
parfeval inside a class method does not update a class property
You cannot broadcast handle objects to a parpool. They simply get cloned and used as independent class instances on the workers....

6 days ago | 1

Answered
Zero Steps Performed in lsqcurvefit Calculation for Matrix Optimization Problem
Seems like the problem has a simple analytical solution, [A,B]=eig( D\diag(P)/(D.') ); A=A.';

6 days ago | 0

Answered
I need that the values of x(1) and x(2) are not higher than 1 using the Genetic algorith for optimization
ub=[1,1,inf];

6 days ago | 1

Answered
Image registration and motion correction
Maybe downsample the images to reduce computation and use imregtform() instead of imregister()?

6 days ago | 0

Answered
3D/2D matrix multiplication without using a loop
Assuming S_r will always be square, B=reshape( S_r*A(:,:), size(A)); %B(:,:,k)=S_r*A(:,:,k)

6 days ago | 0

Answered
Constructor for a class, that accepts name-value pairs for setting properties
With a recent Matlab version, you can do, classdef classX properties Prop1, Prop3; end methods ...

6 days ago | 1

| accepted