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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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...

3 hours 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...

1 day 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.

2 days ago | 1 answer | 0

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

3 days ago | 0

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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...

3 days ago | 0

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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); ...

3 days 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...

3 days ago | 1 answer | 0

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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) ,[...

5 days ago | 0

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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...

5 days 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); ...

5 days ago | 0

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

7 days 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);...

8 days ago | 0

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Answered
nonlinear spline fit with unknown upper bound of interpolation domain
The upper bound is way larger than the fitted parameters at x < 6, causing an extremly large curvature at x > 6 which makes the ...

11 days ago | 0

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Answered
Differentiating in one direction using FFT2
fft2(u) is equivalent to fft( fft(u,[],1) ,[],2), if that helps at all. Truthfully, it doesn't appear that you need to use fft2...

12 days ago | 0

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Answered
need to vectorize efficiently calculating only certain values in the matrix multiplication A * B, using a logical array L the size of A * B
Is v much smaller than m or n? If so, one approach might be with an outer product decomposition: L=sparse(L); %if L was not pre...

12 days ago | 1

Answered
shared colorbar for specific plots in tiledlayout
Using nestedLayouts from the File Exchange, https://www.mathworks.com/matlabcentral/fileexchange/161736-grids-of-tiled-chart-la...

13 days ago | 0

Answered
MATLAB Optional Function Arguments
Using the arguments block is more robust, but I'm unable to find a way to make multiple inputs independently optional. The way ...

13 days ago | 2

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Answered
Set number of rows in output variable using indexing within for loop, add variable to new table
I would like to put the two calculated variable columns directly after the variable column in the original table. And you want ...

14 days ago | 0

Answered
What happens if the termination condition is satisfied before the constraint in matlab's fmincon?
The only time fmincon will stop without satisfying the constraints (within ConstraintTolerance) is if the MaxItertions or MaxFun...

14 days ago | 0

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Answered
How to remove columns in very large matrices.
Use a sparse matrix, if applicable. matrix=sprand(1750000 , 2000, 1000/1750000); whos matrix tic; matrix(:,1:3:end)=[]; ...

15 days ago | 0

Question

Suppress uitable cell borders
In Excel, there are buttons to select particular spreadsheet cell borders and hide them. Is there an analogous way to suppress t...

16 days ago | 1 answer | 0

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Answered
How to find the mask boundaries?
[Y,X,Z]=find(Mask); S=X+Y+Z; [~,i]=min(S); [~,j]=max(S); [Xmin,Ymin,Zmin, Xmax,Ymax,Zmax] =deal( X(i), Y(i), Z(i), X...

16 days ago | 0

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Answered
How to restart a new backgroundPool
delete(pool) pool = backgroundPool;

18 days ago | 0

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Slim code for smoothing spline fit with predefined knots, concavity and monotonicity
One path would be to obtain the matrix form for the spline interpolator, which I do in the example below using func2mat from th...

18 days ago | 1

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Answered
"isfield" for hidden field in optimoptions
One way: options = optimoptions(@fsolve,'JacobPattern',speye(5)); isNonDefault = ~isequal(options.JacobPattern, optimoption...

19 days ago | 0

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nargin of optional arugments
The function "func" has 3 input arguments, why nargin is 1? There are 5 input arguments, not 3: func(1,arg2=3,arg3=5) func...

19 days ago | 0

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Why is my matrix being multiplied by scientific notation?
That's the default way that double floats are displayed in the command window. It is purely a matter of display. The actual valu...

19 days ago | 0

Answered
How to Simplify Passing Multiple Arguments from Structs in MATLAB Function Calls?
You can use namedargs2cell and comma-separated list expansion to pass multiple name-value pairs,e.g., function main(struct_n,st...

19 days ago | 0

Answered
Check if the value for a field in a struct exists
Watch your struct() syntax, A=struct('a',[]) %field 'a' with empty matrix isempty(A.a) B=struct('a',{{}}) %field 'a' with em...

20 days ago | 0

Answered
Image registration on segmented images
My question is thus : Is it possible to perform an image registration on a segmented image? You could use the segmentation to ...

20 days ago | 1

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