Matt J

Last seen: Today

7,329 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
I want set a threshold minimum of matrix
C=max(A*B,1)

36 minutes ago | 0

Answered
Finding mean of row and column in a 3D matrix
a = mean( X(15:25,5:15,:), [1,2])

21 hours ago | 0

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Question

Incremental median across pages of a 3D array
I am trying to compute the inter-page median, B=median(A,3) of a 3D array A except that A is too large to be held in memory i...

2 days ago | 0 answers | 0

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answers

Answered
Undefined operator '<=' for input arguments of type 'struct'.
It would appear that b= get(handles.TableFitur); has set b to a structure variable, whereas you expected it to be a scalar nu...

2 days ago | 0

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Answered
Remove successive rows from a table where a specific column value is duplicated
idx = diff([inf;findgroups(A.site)])~=0; A = A(idx,:)

3 days ago | 1

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Answered
Separating Matrix Rows into two different vectors
A=[1 3 5;1 5 6;3 9 10;3 5 6;1 4 5;3 5 6; 9 6 7; 1 5 8; 3 6 0]; groups=splitapply( @(X) {X} , A , findgroups(A(:,1)) ); [a...

5 days ago | 0

Answered
Finding longest subvector of equal elements in 5000000 length int-vector.
data=[1,1,1,2,2,3,3,4,4]; sequenceLengths = diff( find( diff([inf,data,inf]) ) ) ; result = histcounts(sequenceLengths, 1:...

5 days ago | 0

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Answered
Efficient method to find all intersections of triangulation edges?
The closed form parametric solution for the intersection of two edges is easily derived using the Symbolic Toolbox: syms xa xb ...

5 days ago | 0

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Answered
Compute approximative common eigenvectors basis between two matrices as a function of tolerance
rather building an approximative common eigenvectors basis X between 2 matrices A and B such as : A X_i = a_i X_i and B X_i = b...

5 days ago | 0

Answered
interpolate 3D plane
https://www.mathworks.com/matlabcentral/answers/723053-solve-plane-equation-with-3-points-and-additional-condition#answer_603073...

5 days ago | 1

Answered
search smaller string array to bigger string array
selected={'a', 'gg' 'c'}; Alllist={'a', 'b' ,'d' 'ee' ,'ff' 'gg'}; mask = ~ismember(selected,Alllist) or mask = ~contains(...

5 days ago | 0

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Answered
Solve plane equation with 3 points and additional condition
You can use my planefit() utility [abc,d]=planefit([p1;p2;p3].'); d=-d; function varargout=planefit(xyz) %Fit 3D plane to ...

6 days ago | 0

Answered
Sort a n array for maximum number of recurring values and storing the indexes corresponding to erased components
a=[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,9]; s=diff([inf,a])~=0; ...

7 days ago | 0

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Answered
how I can draw the graph for system of equation when x and y variables are coming inside the coefficients matrix.
A system of 2 equations in 2 unknowns generally has a finite number of solutions. It therefore does not define y as a function o...

7 days ago | 1

Answered
How to plot this implicit function？
It doesn't appear to be a very interesting function. fun=@(Delta,f) (9*(Delta/10)^(1/2))/125 + (pi - atan((18*f*pi*(Delta/10)^(...

8 days ago | 0

Answered
Summing up rows of a cell containing 3D matrices
C=reshape( cat(2,Cell{:}) ,[30,30,5,5,30]); Final=reshape( sum(C,3) , 30,150,30);

8 days ago | 1

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Answered
How to find the first zero element in any column of a m by n matrix
I don't understand what your posted code is trying to accomplish, but you can find the first zero in each row without looping as...

8 days ago | 0

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Answered
Generating mathematical equation from known discrete values of frequency, amplitude and phase
No, there is no reason why a closed form equation would exist for any arbitrary signal. However, you can interpolate the discret...

8 days ago | 0

Answered
How can I create a 22x22 Matrix from 231 values of the triangular matrix?
load(websave('Tri.mat','https://www.mathworks.com/matlabcentral/answers/uploaded_files/493054/Tri.mat')); N=roots([1,1,-2*num...

8 days ago | 1

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Answered
How do I create a matrix based on another matrix?
NumElem=4; N=[1 0 1 0; 3 0 1 1]; E=zeros(NumElem,3); E(N(:,1),:)=N(:,2:end)

8 days ago | 0

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Answered
Error in fsolve (line 219) fuser = feval(funfcn{3},x,varargin{:}); Caused by: Failure in initial user-supplied objective function evaluation. FSOLVE cannot continue.
This usually means that you didn't test your objective function to verify that it works before giving it to fsolve.

8 days ago | 0

Answered
How can I use fmincon into the SPMD when the parameters of objective function differs from on workers to another?
You can use spmd to create the u data on the workers, but then use a parfor loop to do the optimizations. spmd u=labindex; %c...

9 days ago | 0

Answered
Linear Interpolation code ...
p=interp1(x,y, ceil(x(1)):floor(x(end)) );

9 days ago | 1

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Answered
Multiple Parameters in fmincon
I'm not sure why you are using fmincon for something that has a simple, non-iterative solution: C=[cov1(:).^0,cov1(:),cov2(:)];...

9 days ago | 2

Answered
How to find a value X of given Y close to 0, where the value X comes at the first place
damp_ratio=[ -100.00 -100.00 -100.00 -100.00 -100.00 -100.00 -100.00 100.00 100.00 100.00 100.00 ...

9 days ago | 0

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Answered
Replace diagonals in a matrix
For example, A=rand(10), mask=tril( triu( true(size(A)), -2 ), +2); B=A.*mask

9 days ago | 0

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Answered
ROI of a ring area?
For example, [x,y]=deal(1:1000); dsq=(x-400).^2 + (y(:)-300).^2; ROI = (50^2<=dsq & dsq<=100^2 ); imshow(ROI)

9 days ago | 0

Answered
indexing a set in an array
[k,l]=deal(1:1000); SET=(k.'-k0).^2+(l-lo).^2 < R^2;

9 days ago | 0

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Answered
HOW TO SHIFT COLUMN AND ROW MATRIX
x=repmat([1 2 3 4],4,1); x(6,6)=0 perm=[1,2,5,6,3,4]; x(perm,perm),

9 days ago | 1

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Answered
Calculation of Rotation in 3D space
You can use absor() https://www.mathworks.com/matlabcentral/fileexchange/26186-absolute-orientation-horn-s-method to register ...

9 days ago | 1