# Matt J

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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**Content Feed**

Calculation errors while using subs and det functions

You haven't given us access to the input variables needed to repeat the computation. However, the determinant you are evaluating...

ungefär 16 timmar ago | 0

Extracting from boxchart function the median, quartiles, and whisker data.

I don't believe those quantitites are directly available as permanent property data. When you position the cursor over one of th...

ungefär 16 timmar ago | 1

How to define the order of layers/plots and axes?

1) Hfig=figure('Visible','off); p(1) = plot(...); p(2) = scatter(...). p(3) = line(..); p(4) = fill(...), p(5) = imagesc(...) ...

en dag ago | 0

error in the process of symbol operation of the matrix

Nothing is wrong with T, though possibly you didn't scroll down far enough to see the definitions of all the sigmas.

en dag ago | 0

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...

2 dagar ago | 0

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_hierarchy,"Copepoda");

3 dagar ago | 0

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...

3 dagar ago | 0

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;...

3 dagar ago | 0

| accepted

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;

3 dagar ago | 0

Fit gaussian surface on 3D data

Using gaussfitn from, https://www.mathworks.com/matlabcentral/fileexchange/69116-gaussfitn load Image %cropped to include onl...

3 dagar 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...

4 dagar ago | 2 answers | 0

### 2

answersSolve 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...

4 dagar ago | 0

| accepted

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...

5 dagar ago | 0

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...

5 dagar ago | 0

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...

6 dagar ago | 0

| accepted

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.

6 dagar ago | 0

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) ;

6 dagar ago | 0

How do I fit two data sets to each other?

Sounds like a 1D image registration problem. Maybe consider imregtform.

7 dagar ago | 0

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...

8 dagar ago | 0

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...

8 dagar ago | 0

| accepted

How can I make the numeric edit field blank?

You can set the ValueDisplayFormat property to %0.0d

8 dagar ago | 1

| accepted

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...

8 dagar ago | 0

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...

9 dagar ago | 1

| accepted

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;...

10 dagar ago | 0

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...

10 dagar ago | 0

| accepted

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))

11 dagar ago | 0

| accepted

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...

11 dagar ago | 1

| accepted

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...

12 dagar ago | 0

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,...

12 dagar ago | 0

change outputlayer in layergraph object

For example, lgraph=layerGraph(regressionLayer) layers=lgraph.Layers; layers(end).Name='newName'; lgraph=layerGraph(la...

12 dagar ago | 0

| accepted