Matt J

Last seen: Today | 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
pinv failing on single precision matrices
I don't think it's a bug. Contrary to what you claim, the matrix is not very invertible, showing a condition number of ~1e7, fo...

ongeveer een uur ago | 0

Answered
freeze some weights inside of a fullconnected layer
It is possible with a custom layer. See this recent, related thread, https://www.mathworks.com/matlabcentral/answers/2174601-ho...

1 dag ago | 0

Answered
Cell2table issues when a numerical column is read as strings
I would also have many columns, some of which could be made up of: (a) all doubles (b) a mix of empty strings (e.g., ' ', ' ...

2 dagen ago | 0

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Answered
Pagewise multiplication along a dimension without using a for loop?
No, but looking at your code, I would guess that the speed is being encumbered much more by the operation length(X(1,1,1,:)) tha...

2 dagen ago | 1

Answered
Add a class folder to path
Nothing is wrong. @-directories should not and do not need to be on the path as long as their parent directory is. You can auto...

3 dagen ago | 0

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How to read all rows of an Excel with missing rows included?
ActiveX can be used to determine the last row/column of the worksheet: Then, you can force readcell to read in a larger range wi...

3 dagen ago | 0

Question

Make gca() responsive to appDesigner axes clicks
I have an appdesigner app such as below with a uipanel containing regular images (not uiimages). I also have many, many standal...

4 dagen ago | 1 answer | 0

1

answer

Answered
polyshape not closing a circle
An added complication is that the resulting union may have multiple regions, so I cannot just duplicate the first vertex to the ...

4 dagen ago | 0

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Answered
How can I create multiple function handles in a for loop?
The best would be to just have a matrix-valued function, fun=@(x) x.^2-mymat(:).*x+mymat(:) but you could make a cell array of...

5 dagen ago | 0

Answered
Filtering Blobs on a Binary Image
If you can form an under-estimate of the extent of the blobs, let's call them sub-blobs, then you can fit a Gaussian lobe to the...

5 dagen ago | 0

Answered
Why does the Code Analyzer flag this as an error?
Mathworks Support has classified it as a bug.

6 dagen ago | 1

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Answered
How do you change the output dimension of a NN layer?
Should I flatten the inputs and then concatenate them similar to this example? Probably. See if the attached network does what...

7 dagen ago | 0

Answered
Display a small matrix as a gray scale image
T2 =[ 0.4706 0.9804 0.8392 0.3216 0.9804 0.8392 0.3216 0.4706 0.8392 0.3216 0.4706 0.9...

7 dagen ago | 0

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Answered
How to freeze specific neuron weights in a feedforward network during training process?
I don't think you can do it without the Deep Learning Toolbox. If you have the Deep Learning Toolbox, you can define a custom la...

8 dagen ago | 0

Answered
Please help with this multiplication problem
You can multiply directly. Example: [m,n,r]=deal(3,4,2); A=rand(m,1,r); B=rand(1,n,r); C=A.*B; whos A B C

8 dagen ago | 0

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Answered
sub2ind() errors out with NaN inputs - handled differently since R2024a
You can get the old behavior back if you need it, Sub2Ind([ 3 5 7], [ 3 3], [2 2], [1 nan]) function out=Sub2Ind(sz,vararg...

8 dagen ago | 0

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Answered
Non-linear constraints format for GA using solve function
I would formulate it as, N=numel(Pos_Input_mtx); problem.Constraints.c1=abs(Pos_Input_mtx(:)-Pos_Input_mtx(:)') >= (1-eye(N)...

8 dagen ago | 0

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Answered
Summing function handles of multiple variables across one of the variables
Nesting function handles n-fold is going to be very inefficient, and is usually not a good idea. Usually, it is best to vectoriz...

9 dagen ago | 0

Answered
Error using trainNetwork Invalid training data. For classification tasks, responses must be a vector of categorical responses. For regression tasks, responses must be a vector
Instead of using Matlab's dicePixelClassificationLayer, you can try the following custom output layer: classdef GeneralizedDice...

11 dagen ago | 0

Answered
Ifft2 results do not match that of irfft2 in Pyhton
I'm not a Python user, but if rfft2 only gives you positive x-frequencies, I would imagine it also only gives you positive y-fre...

12 dagen ago | 0

Question

Three dots at the end of a line of code
Why does one of my lines of code have three dots enclosed in a box? What does it mean? Clicking on it does nothing.

13 dagen ago | 1 answer | 0

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answer

Answered
Looking for linear system Ax=0 precision improvements
s=max(abs(A),[],1); x = null(A./s)./(s')

13 dagen ago | 0

Answered
Finding x and y values of minimum z in 2-variable function.
The continuous minimum can't be at (5,2) as you claim. Direct evaluation shows that the value of z at (5.5,10) is lower. loopi...

13 dagen ago | 0

Answered
Using fft and ifft with less frequencies than input points
What I would want to do, is to insert an N, f.e. N=100, but get an array 10001x1. %Grid Nx = 100; L = 10; dx = L/(Nx-1); ...

13 dagen ago | 0

Question

Why does the Code Analyzer flag this as an error?
Why does the Code Analyzer flag this code as an error? It runs fine: try error("It's bad") catch ME warning('Error...

14 dagen ago | 2 answers | 0

2

answers

Answered
How to fastly calculate this real number matrix manipulation?
e=(1:A)'; I=reshape(e,1,1,[]) == repmat( e,1,B); Xp=permute(X,[3,2,1]); D=X./(X-Xp); D(I)=1; M = ipermute( prod(D,1) ,[...

15 dagen ago | 0

Answered
How to solve the error generated while defining custom FFT layer?
Your predict() method is written to expect that the input X will be a cell array. It's not clear why you expect this, but you sh...

16 dagen ago | 0

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Answered
How do I edit a loop to be able to store the variables and outputs used in each loop in a way which can be graphed?
D = 0.3 k = 0.0002 Rvalues = 10^4:10^5:10^8; nR=numel(Rvalues); X=nan(1,nR); for i=1:nR R=Rvalues(i); ...

16 dagen ago | 0

Answered
reshape 4-dimension array
Download this File Exchange package, https://www.mathworks.com/matlabcentral/fileexchange/115340-block-transposition-permutatio...

17 dagen ago | 0

Answered
Speed up this bottleneck line of code
If you can construct c in transposed form, there are some savings to be had, n = 10000; m = 5000; k = 20; a = rand(n,m);...

18 dagen ago | 0

| accepted