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Matt J


5.522 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
Conditional function on matrix
vals=[1,10,5]; Kd=vals( discretize(Kt,[-inf,0.2,1.09*c2,+inf]) );

ongeveer 10 uur ago | 0

Answered
HELP DIFFERENT LINESTYLE ON THE SAME CURVE
Just split x,y into two subsets and plot each subset as a separate line: idx=x<50; x1=x(idx); y1=y(idx); x2=x(~idx); y2=y(~id...

ongeveer 10 uur ago | 0

| accepted

Answered
Convert cell arrays to 4-D array
Where C is your cell array: M = reshape( cat(3,C{:}) , [256,256,10,35]) EDIT: Or M = reshape( cat(3,C{:}) , [256,256,35,10...

ongeveer 15 uur ago | 0

| accepted

Answered
Ax=b question
You could use intlinprog. Assuming WNLOG that the manipulated b value is b(1), N=numel(b); f=[-1,zeros(1,N)].'; Aeq=[+100*f...

1 dag ago | 0

Answered
Cross Product of an Array
This way avoids repmatting, which may be desirable when N is large. M = your 3xN matrix v = your 3x1 vector result=xprodmat...

1 dag ago | 0

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expectation of random numbers
You can't do it. The D(i) are statistically independent, and so offer no information about what comes next.

1 dag ago | 0

Answered
How can I mean multiple matrices, element by element in a n*n cell array?
If I call your cell array C, M=cell2mat(reshape(C,1,16,[])); result = mean(M,2)

2 dagen ago | 0

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Answered
Failure in initial objective function evaluation. FSOLVE cannot continue.
Instead of XN, in this line F(1) = Xn2 + Xo2 + Xo + XN + Xno - 1; should it be Xn?

5 dagen ago | 0

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Answered
How to compute the homography
tform = projective2d(H); newImage = imwarp(oldImage,tform);

5 dagen ago | 1

Answered
What is lambda in lsqcurvefit?
The lambda returned by lsqcurvefit are not Levenberg-Marquardt parameters. They are the Lagrange multiplers at the solution. If ...

5 dagen ago | 0

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Answered
How fmincon shifts x0 when it does not strictly satisfy the upper and lower bounds?
I don't know precisely how the shifting algorithm works, but I think it's safe to assume that it is independent of the objective...

6 dagen ago | 0

Answered
Find matrix rows that have 3 common values, store the rows and the values
I'll call your original 5 column matrix A. D=cell(4,1); a5=A(:,5); As=sort(A(:,1:4),2); for i=1:4 %small loop ...

7 dagen ago | 0

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Answered
fminunc stopped because it cannot decrease the objective function along the current search direction.
You will need to use a dedicated function for computing the log-sigmoid. Combining log and sigmoid as separate functions is nume...

7 dagen ago | 0

Answered
Issues in Matrix multiplication
A somewhat less efficient solution (but which uses no 3rd party files) is, A=rand(6,6,100); B=rand(6,1,100); C=sum( A.*reshap...

7 dagen ago | 1

Answered
Issues in Matrix multiplication
Use mtimesx from the File Exchange https://www.mathworks.com/matlabcentral/fileexchange/25977-mtimesx-fast-matrix-multiply-with...

7 dagen ago | 0

Answered
Move logical array by one
id2=circshift(id1,-1)

8 dagen ago | 0

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Answered
Extract rectangular grid from triangulation
I think you are looking for griddata().

8 dagen ago | 0

Answered
How do I get the mean of always 4 columns
One way is using sepblockfun, downloadable from here https://www.mathworks.com/matlabcentral/fileexchange/48089-separable-block...

8 dagen ago | 0

Answered
Compute an Orthogonal Matrix
No, this is generally not possible. When all the eigenvalues of A are distinct, for example, the (orthonormalized) eigenvectors ...

9 dagen ago | 0

Answered
How to calculate covariace of two random variable
cov(x(:),y(:))

9 dagen ago | 0

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Answered
how i can find these branching point
[I,J] = find(binaryimg<max(binaryimg(:))/2); IJ = [I,J]; [~,idx] = min(IJ*[1 1; -1 1; 1 -1; -1 -1].'); Corners = IJ(idx,:); ...

9 dagen ago | 0

Answered
I am trying to find the corners of the "rectangular" shapes. This code is working very well. But I dont know exactly how it works. Can you explain me ??
Maybe this image will help. The corners of a polyhedron will maximize/minimize the intercept of lines of a certain slope - it's ...

9 dagen ago | 0

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Answered
Create a free cubic spline that passes some certain points
The spline command would be one way https://www.mathworks.com/help/matlab/ref/spline.html

9 dagen ago | 0

Answered
values of equation in last iteration in fmincon
The computation of xw1 is a trivial one-liner. Just compute it separately from the optimal X given to you by fmincon, xw1=sum( ...

9 dagen ago | 0

Answered
Overlaying and Comparing Two Sets of Co-Ordinates
I haven't used it myself, but this implementation of Iterative Closest Point seems pretty popular https://www.mathworks.com/mat...

9 dagen ago | 0

Answered
two conditions on two 8*256 matrices
There are lots of knapsack problem solvers on the File Exchange https://www.mathworks.com/matlabcentral/fileexchange?q=knapsack...

10 dagen ago | 0

Answered
Combining cells within a cell array that have intersecting values
You should just represent your shapes as polyshape objects. Then it is easy to weed out redundant vertices using the simplify()...

11 dagen ago | 1

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Answered
Curve fitting & Plotting On Logarithmic y, linear x
You can change the scale of the plot from linear to log just by doing hAx.YScale='log'; where hAx is a handle to your axis.

11 dagen ago | 0

Answered
Skip empty array in plot legend?
Why not something like this? allLines=[a,b,c,d]; allStrings={'blue line', 'level1', 'level2', 'exceed const lims'}; leg...

12 dagen ago | 0

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