Matt J

Last seen: Today | Active 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.

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Answered
Is it possible to handle a slider with an 'on-line' update? I mean, updating the value continously during the sliding.
Yes, use the ValueCHangingFcn callback https://www.mathworks.com/help/matlab/ref/uislider.html#buicpgg-1_sep_shared-ValueChangi...

11 hours ago | 0

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How to extract rows of data according to text containing specific words in cells in Matlab
copepods= contains(C.object_id,"cruise2012") & ... contains(C.object_annotation_hierachy,"Copepoda");

1 day ago | 0

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lsqcurvefit does not follow convergence criteria in summation.
After the fit has converged (but not giving a useful result) I checked for the convergence criterion and it wasn't replaced with...

1 day ago | 0

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Unrecognized function or variable 'x0'.
Relocate the last 2 lines from newmintafun1 and make x0 the correct length. x0 = [10; 6; 4; 3; 4; 3; 2; 3; 18; 7; 25; 10; 5; 5;...

2 days ago | 0

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How to create big matrix that the item is small matrix
See, How to Generate a Block Toeplitz Matrix. Then replace the last D block with F, Matrix(end-11:end,end-11:end)=F;

2 days ago | 0

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Fit gaussian surface on 3D data
Using gaussfitn from, https://www.mathworks.com/matlabcentral/fileexchange/69116-gaussfitn load Image %cropped to include onl...

2 days ago | 1

Question

Reloading handle objects from .mat files
Why does isequal() return false when the reloaded handle is compared to the original handle, in the code below. h=plot(1:5); s...

3 days ago | 2 answers | 0

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Solve linear equation in matrix form with least square method
If I use (A.'*A)\(A.'*b), i can get the result An even easier and more accurate way to get it is, x=A\b and that is the meth...

3 days ago | 0

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Interpreting the results of 'fsolve'
It means fsolve thinks it found a solution. Whether you can "trust" the solution is an open-ended question. It depends on the ap...

4 days ago | 0

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using matchpairs when objects have different capacities
Then you are not seeking pairings. Therefore, matchpairs will not apply. But you can probably use minL1intlin from this FEX down...

4 days ago | 0

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Coding volume segmentation with multiple thresholds (CT data)
I can iterate through different CT number thresholds, using a function to create a binary mask (a 3D matrix) at each. However, I...

4 days ago | 0

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Attempt to grow array along ambiguous dimension
In this line, idealF1(distance4 <= D01)=0; you have not checked the size of distance4 and of idealF1.

4 days ago | 0

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want to plot ellipses with different a and b values in x^2/a^2 + y^2/b^2 = 1 in Matlab 3d plot
Simplie enough. a=0.1;b=0.15; fsurf(@(x,y) x.^2/a^2+y.^2/b^2) ;

5 days ago | 0

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How do I fit two data sets to each other?
Sounds like a 1D image registration problem. Maybe consider imregtform.

6 days ago | 0

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Trying to do an if/and statement on a vector but have an addition apply to only one element of vector
I think a better method would be to update the compass position incrementally, using the attached file cumangle.m t=linspace(-1...

6 days ago | 0

Answered
generate all variations on a 20-mer, that are 1 to 4 mismatches away
Using blkColon from this FEX download, https://www.mathworks.com/matlabcentral/fileexchange/115340-block-transposition-permutat...

6 days ago | 0

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Answered
How can I make the numeric edit field blank?
You can set the ValueDisplayFormat property to %0.0d

7 days ago | 1

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How can we increase/decrease the number of triangles in a triangulation that is created from a polyshape object?
Another way: p1=nsidedpoly(6); p2=p1.scale(0.5); P=subtract(p1,p2); P=subTri(P); for i=1:3 P=splitTri(P); end pl...

7 days ago | 0

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creating multiple arrays that all have the same name with different number
You wouldn't do that. You would instead combine all the calculations into a single matrix Gcr: density = 1000; g = 9.8; gamma...

8 days ago | 1

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Answered
How can we increase/decrease the number of triangles in a triangulation that is created from a polyshape object?
To increase the number of triangles, you would have to add vertices along the edges, like in the following: p1= polyshape([0,0;...

9 days ago | 0

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How to make the output size of imwarp the same as the input?
There is an OutputView input parameter that will let you control that, https://www.mathworks.com/help/images/ref/imwarp.html#bt...

9 days ago | 0

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Answered
Optimization to fit a curve to data (problem with the InitialPopulationMatrix)
Instead of x = 1:size(Data,2); perhaps try a more normalized range of x, e.g., x=linspace(0,1,size(Data,2))

10 days ago | 0

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Solving for different types of variables on large dataset with lsqnonlin
You could imoplement a nested optimization, with the outer optimization over a done with fminsearch while that over T can be don...

10 days ago | 1

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How to assign elements in a vector to an entry in a structure array variable?
You could also consider using a table instead, Names=["Jon","Phil","Bob","Gary"]'; T=table(Names,nan(size(Names)), 'Var',["N...

10 days ago | 0

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How to assign elements in a vector to an entry in a structure array variable?
You could also consider using dictionaries instead of a struct array, Names=["Jon","Phil","Bob","Gary"]; D=dictionary(Names,...

11 days ago | 0

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change outputlayer in layergraph object
For example, lgraph=layerGraph(regressionLayer) layers=lgraph.Layers; layers(end).Name='newName'; lgraph=layerGraph(la...

11 days ago | 0

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Answered
I have data in 3D array and I know indices in the first two dimensions. How do I collect all data without for loop?
One way Data(:,:,1) = [1,2,3 4,5,6 7,8,9]; Data(:,:,2) = [11,22,33 44,55,66 77,88,99]; idxRow = [1,1 ...

11 days ago | 0

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How to assign elements in a vector to an entry in a structure array variable?
But I want to avoid loops because my code is already within another large loop which is slow. When dealing with structs, there ...

11 days ago | 0

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Passing a variable constraint to fmincon
I think this is what you mean, for nn=1:N ynn=y(nn); FUN = @(x)((sqrt((x(1) - a)^2 + (x(2) - b)^2) + sqrt((x(1) - ...

11 days ago | 0

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Answered
Convolutional neural networ for classification problem with matrices instead of images
Since I'm dealing with .csv files i have to use the "tabularTextDatastore" command to create the datastore. No, just use an ima...

12 days ago | 0