Matt J

Last seen: 1 day ago | Active since 2009

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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.

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Answered
How to use validation dataset in iteration-based deep network training?
Sure, use the network to make some predictions, https://www.mathworks.com/help/deeplearning/ref/dlnetwork.predict.html

10 hours ago | 0

Answered
What are the differences between fitrnet and trainnet?
Unlike fitnrnet, the L-BFGS algorithm used by trainnet does not seem to use a line search. That might have had something to do w...

12 hours ago | 0

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A simple question regarding image processing
I see that some pixels are darker than others, but no pixels that are jet black. If you have some criterion to decide which pixe...

15 hours ago | 0

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Answered
define an objective function with user defined number of variables in fminunc()
The only way fminunc knows the number of variables is by looking at numel(x0) where x0 is the initial guess: xmin = fminunc(fun...

1 day ago | 2

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Answered
Deconvolution of two different Gaussians
If you know a priori that all the signals are Gaussians, then deconvolution would not be the best way to recover espread. You kn...

1 day ago | 0

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Displaying a struct containing gpuArray fields takes an extremely long time in R2024b
Here's a possible workaround: c.a=1; c.b=2; c.data=gpuArray.rand(100,100,100,'double'); tic; c, toc c = struct with...

1 day ago | 0

Answered
Finding a circle in a 2D array
load P BW=median(P(:))-P>50; BW=bwpropfilt(bwareaopen(BW,100),'Eccentricity',6,'small'); c=vertcat(regionprops(BW,'Cent...

1 day ago | 0

Answered
imerode/imdilate use convolution?
No, imdilate is a sliding window max() operation, which is nonlinear, and therefore not, in general, a convolution. Similarly im...

2 days ago | 0

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Answered
Take 3x3 nearest neighbours round centroids of all spots and find the median of their mean
sz=size(IM); centroidIdx=sub2ind(sz,y1,x1); T=combinations(1:3,1:3); delta=sub2ind(sz,T{:,2},T{:,1})'-(sz(1)+2); resu...

3 days ago | 0

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Answered
Take 3x3 nearest neighbours round centroids of all spots and find the median of their mean
movingMean=conv2(IM,ones(3)/9,'same'); centroidIdx=sub2ind(size(IM),y1,x1); result=median(movingMean(centroidIdx))

3 days ago | 0

Question

Displaying a struct containing gpuArray fields takes an extremely long time in R2024b
I find that when I create a struct (or object) whose fields are large gpuArrays, it takes an extremely long time (1-2 minutes) t...

3 days ago | 2 answers | 0

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answers

Submitted

gaussfitn
Fit N-dimensional scattered points with Gaussian+constant

4 days ago | 10 downloads |

Answered
MINLP problem in MATLAB with both integer constraints and nonlinear equality constraints
If, as @Torsten mentioned, you are in the situation where the equality constraints only depend on the continuous variables, then...

5 days ago | 0

Answered
how to use fmincon to optimize a functio with more than one control vector where the control vectors used in constrains also?
Use the problem-based optimization framework to launch fmincon. It will look approximately like, p=optimvar('p',pi,pj); X=opti...

6 days ago | 0

Answered
Fit a linear equation to obtain coefficients (constants)
I have a linear equation P = a + bM + c(Y-1) + d(M(Y-1)) where a, b, c and d are coefficients (constants). P, Y and M are known...

8 days ago | 1

Answered
MINLP problem in MATLAB with both integer constraints and nonlinear equality constraints
Such problems usually do not have solutions (EDIT: unless the equalities depend only on the continuous variables), since a nonli...

8 days ago | 1

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Answered
parallel computing apply to my problem
Skipping the symbolic operations will speed things up, tic; t=linspace(0,0.1,1000)'; tsquared=t.^2; [a...

9 days ago | 0

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Class Property Validation for the Contents of a Cell Array Property?
You can do it, but you would have to define your own validation function, https://www.mathworks.com/help/matlab/matlab_oop/prop...

9 days ago | 2

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Question

Loading user-defined classes from .mat files absent the classdef
At one time, if I had a .mat file with a user-defined class variable, but lacked the classdef file, loading the .mat file would ...

9 days ago | 1 answer | 0

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Question

Why does .mat file previewer take so long?
I often wish to preview the contents of a .mat file in the Current Folder browser. Some of my .mat files are quite large, which ...

9 days ago | 1 answer | 0

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answer

Submitted

Further tools for analyzing objects in N-dimensional images
A collection of tools to supplement bwpropfilt, bwareaopen, and the like.

11 days ago | 3 downloads |

Question

How do I import my MATLAB path preferences when I install MATLAB on new computers?
I have a new computer with Matlab 2024b newly installed on it and am looking to import preference settings (mainly desktop layou...

11 days ago | 1 answer | 0

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Question

Command Window prompt stays in view during Run Section
I find, in R2024b (I haven't checked other versions), then when running sub-sections of code, for example with , the command li...

11 days ago | 1 answer | 0

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Answered
how to fft2 with dlarray?
You haven't explained the difficulty you are experiencing, but I assume it is that an fft(), but not an fft2() command is availa...

12 days ago | 0

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Answered
Iteratively selecting rotation angle for alingment
Use imregtform if you are aligning images. If you are aligning points, use this, https://www.mathworks.com/matlabcentral/fileex...

12 days ago | 0

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Ensuring Non-Negativity and Constraints Satisfaction in Regression with ReLU in MATLAB
You cannot request that trainNetwork strictly enforce constraining (in)equalities using a constrained optimization algorithm, if...

12 days ago | 0

Answered
How to stabilize the edge effects in a cubic B-spline?
This FEX file allows you to specify extrapolation conditions on the B-spline coefficients, https://www.mathworks.com/matlabcent...

13 days ago | 1

Answered
How come fsolve is exceeding evaluation limit?
I don't quite understand the physics of your problem, but I have the impression that x(3:5) are meant to be non-negative. Hence,...

15 days ago | 0

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ellipse fit of xy data
I think the arc is too short to get a good elliptical fit. Why not a circular fit? Qualitatively at least, it looks pretty good:...

15 days ago | 0

Answered
Why does this special case for associativity of a matrix product with a hadamard product hold true?
It is clear why this happens when n=1, i.e, when A*B is an outer product. But now for arbitrary n, the matrix product can be wri...

19 days ago | 1

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