Matt J

Last seen: Today

7.733 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
How can concatenate matrices with dimension expansion.
permute( cat(3,img1,im2), [3,1,2]);

alrededor de 11 horas ago | 0

Answered
Plotting a 3D mode shape by revolving 2D datapoints (in the r-z-plane) of an axisymmetric geometry around the z-axis
I can't follow most of what you posted, but if you just want to generate a surface/solid of revolution, you can use cylinder() ...

alrededor de 14 horas ago | 0

Answered
making a 2d image from 3d shape
It seems like it would be better if you would just generate your spheres direclty as a 3D image volume. Then you could just use...

alrededor de 14 horas ago | 0

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Zero points on graph
xIntercept1=roots(TL1); xintercept2=roots(TL2); yIntercept1=polyval(TL1,0); yIntercept2=polyval(TL2,0);

alrededor de 15 horas ago | 0

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Answered
Extract objects from binary image
Something like this perhaps, BW=bwareafilt(~yourBinarizedImage,3); regions=regionprops(BW,'Image');

alrededor de 16 horas ago | 0

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Changing the same property of some axis children using subsasgn
I assume you know that subsasgn is called implicitly whenever you make an assignment statement, as in the following: [toHide.Vi...

alrededor de 21 horas ago | 1

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Answered
Area of a implicit curve
Here is a very similar strategy based on alphaShape instead of polyshape. It is slower, but IMO handles the bounding rectangle a...

alrededor de 24 horas ago | 2

Answered
Perimeter of a implicit curve
Perhaps as follows (see also this thread) plotRange=[-1,+1, -1,+1]*8; plotCorners=[-1 1;1 1;1 -1; -1 -1]*8; f=@(x,y) (sin(x...

1 día ago | 0

Answered
The determinant of a unitary matrix is 0
Matlab's det involves taking the product of long matrix diagonals. This can overflow or underflow very easily. The following mig...

1 día ago | 1

Answered
The determinant of a unitary matrix is 0
Determinant calculations for large matrices are numerically delicate (which is why they're often avoided). There are other/bett...

1 día ago | 0

Answered
display of curve information matlab
See Add Legend to Axis.

1 día ago | 0

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Answered
curve shifting on horizontal axis
For example, x=linspace(-pi,pi,1000); y=exp(x); plot(x(:)+(0:5)*10,y); axis([0,100,0,10]); legend

1 día ago | 0

Answered
Area of a implicit curve
Perhaps as follows? plotRange=[-1,+1, -1,+1]*8; plotCorners=[-1 1;1 1;1 -1; -1 -1]*8; f=@(x,y) (sin(x).*sin(y)-0.5); fp=fi...

1 día ago | 2

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Answered
Matrix Dimension Must Agree
theta and l do indeed have different lengths, so it is not clear what you are trying to do in your calculation of Eteta. n = 37...

2 días ago | 0

Answered
How to find all the possible feasible solutions to a integer linear programme?
For R^20, yes. Just do an exhaustive search, [x{1:20}]=ndgrid([0,1]); x=reshape( cat(21,x{:}) ,[],20).'; feasible = x(:, al...

2 días ago | 0

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Answered
Optimization of Rosenbrock function
fun = @(x)100*(x(:,2) - x(:,1).^2).^2 + (1 - x(:,1)).^2 - 108.32; [x,fval]=lsqnonlin(fun,[0,0],[1,1])

2 días ago | 0

Answered
Basic question of convolution
But, when the equation is y[n] = x[n-1] * h[n+1], how can I make n-1 and n+1?? There is no need to in this case. because of the...

2 días ago | 1

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Answered
3D best fit curve from x,y and z data points
For the linear case, you can use linear3dFit from this FEX submission. As the others have said, however, we need to know the spe...

3 días ago | 0

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Answered
How to merge two table coulmns into one column?
T1=table([1;2;3],'VariableNames',{'X'}); T2=table([3;6;7],'VariableNames',{'X'}); x=str2double(string(T1.X)+string(T2.X))

3 días ago | 1

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Answered
Select image region using point coordinates
regions=regionprops(yourImage,'PixelList'); detector=@(s) ismember([x,y], s.PixelList,'rows'); find( arrayfun( detector , ...

3 días ago | 1

Answered
Determining internal coordinates of a rotated ellipsoid
Why is triangulation part of the strategy if you want actual points inside the ellipsoid? If you have the means to sample the su...

3 días ago | 0

Answered
Quadprog solver stalled, constraints satisfied.
Well, because in the first case you are using a non-default ConstraintTolerance, of course. That changes the conditions when the...

3 días ago | 0

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Answered
How to download polyparci file and run it with matlab code becsause there iss no polyparci command in-built of MATLAB
This might be it: https://www.mathworks.com/matlabcentral/fileexchange/39126-polyparci?s_tid=srchtitle

3 días ago | 0

Answered
How to do Interpolation for paired images.?
This might help, https://www.mathworks.com/matlabcentral/fileexchange/22665-n-dimensional-fourier-interpolation

3 días ago | 0

Answered
Plotting a logical function if a value is greater than 0
Something like this? tor=1:10; AG=tor>5; y=double(AG); y(~AG)=nan; h=plot(tor,y); xlim([min(tor),max(tor)]);xlabel 'tor',...

3 días ago | 0

Answered
Implicit plane curve discretization
fp=fimplicit(@(x,y) x.^2 + 2*y.^2 - 1); %Example Points=[fp.XData;fp.YData]

3 días ago | 3

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Answered
Selecting a block of values in a matrix.
Loops are not needed. Using sepblockfun (which you must Download) yourMatrix=randi(100,10); %example result=repelem(sepblock...

3 días ago | 0

Answered
How to draw 2D object with plot 3D matlab
The command cylinder() will be helpful. This example in particular, https://www.mathworks.com/help/matlab/ref/cylinder.html#mw_...

4 días ago | 1

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Answered
How to add uniform noise to image with median and standard deviation
I've never heard of "noise" with non-zero mean/median, but generating it is straightforward, delta=standardDeviation*sqrt(12); ...

4 días ago | 0

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Answered
How to Check if a cell equals a word in a table
As an example, x=cell2table({'dog','paper','cat','fish','paper'}.') paper=nnz( string(x{:,1})=="paper") otherstuff=size...

4 días ago | 0