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Matt J


Last seen: Today
7.029 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
How can I convert 100 X Y and Z coordinates generated randomly in the form of a 100x100x100 matrix
If you mean you want a 100x100x100 binary array A with one hundred randomly located entries where A(i,jk)=1, then A=false(100...

etwa 3 Stunden ago | 0

| accepted

Answered
fmincon MATLAB function using gradient
Because of the discontinuity at x1=0 and x2=0, you need to optimize over each quadrant separately. s=[+1,+1; %quadrant signs ...

etwa 23 Stunden ago | 0

Answered
Mean Variance portfolio selection with l1-norm
Sure. Minimizing a quadratic subject to linear constraints is exactly what quadprog is for.

ein Tag ago | 0

Answered
How to perform image registration on GPU
If you only need to register translation, you can use normxcorr2() which is GPU-supported https://www.mathworks.com/help/images...

ein Tag ago | 0

Answered
how to find coordinates of each brick corners using matlab
After applying imopen() like ImageAnalyst recommends, you could download pgonCorners and apply it as in this example in this exa...

ein Tag ago | 0

Answered
What is wrong with my for loop?
It seems clear that when i=j, the left hand side of K((j*s-j-1):(i*s-i-1), (j*s-j-1):(i*s-i-1)) = k(1:s,1:s); will be 1x1 wher...

ein Tag ago | 1

Answered
Drawing 4-sided polygons around objects
This will help to find the corners of the boxes. https://www.mathworks.com/matlabcentral/fileexchange/74181-find-vertices-in-im...

ein Tag ago | 0

Answered
Stop chatting, MATLAB!
Just a guess, but you might try going into Preferences>>General and unchecking the option to send telemetry info back to MathWor...

3 Tage ago | 0

Answered
How can we refer world coordinate to image coordinates??
You have world2Intrinsic() https://www.mathworks.com/help/images/ref/imref2d.worldtointrinsic.html

5 Tage ago | 0

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Answered
Cone constraints with mixed integer programming
My approach would be to reduce this to a 1-variable minimization over x(11) and solve that with fminsearch, [Combinations{1:10}...

7 Tage ago | 1

Answered
Find nonzero elements in 5x5 matrix (diagonal, vertical, horizontal line)
For example, to search for a column string, A =[ 1 4 4 4 5 3 1 4 1 4 5 ...

8 Tage ago | 0

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Answered
How can I fit multiple lines through a common y-intercept?
p=[x(:).^[1,0] ,0*x(:); 0*x(:),x(:).^[0,1]] \[y1(:);y2(:)]; m1=p(1) b=p(2) m2=p(3)

8 Tage ago | 2

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Answered
fmincon very slow for a small scale problem
Don't use Symbolic Toolbox operations. Remove all the sym operations and just convert fnsum to a numerical objective function.

8 Tage ago | 0

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Answered
Double summation of a matrix
The expression in your .jpg file, if it needs to be evaulated for all p,q would be SML=conv2(ML,ones(N+1),'same')

8 Tage ago | 0

Answered
Prevent a figure/axis from being made current manually
Like Walter mentioned, setting the figures HandleVisibility to off seems to do the job.

8 Tage ago | 1

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Answered
Double summation of a matrix
In recent Matlab, you can do sum(matrix,'all') or more generally you can do sum(matrix(:))

8 Tage ago | 0

Answered
Why Matlab tells the following A*A^T matrix is not a positive Semi-definite Matrix ?
Yes, it is positive semi-definite. But Matlab's ability to detect that is limited, because finite precision prevents it from com...

8 Tage ago | 0

| accepted

Question


Prevent a figure/axis from being made current manually
Is there a way to disable the ability of the figure window to automatically become the current figure when a manual user action ...

8 Tage ago | 2 answers | 0

2

answers

Answered
Why matlab live editor and matlab script gives different rank calculation result for the same matrix ?
Probably because you copy-pasted the values of M from the screen to one of the scripts.

10 Tage ago | 0

| accepted

Answered
How to rotate 3D cube so that one face is normal to a given axis
If I can choose the missing rotation angle freely, then here is one solution. % Centre of system coords_source_xyz= [-0.5,...

10 Tage ago | 0

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Answered
Fitting Data from a matrix to polynomial
A very relevant example: https://www.mathworks.com/help/curvefit/fit.html#bto_zh5-3

10 Tage ago | 0

Answered
How to solve a nonlinear equation?
[x,fval] = fzero( @(x) x^(8.5)+3*x.^2-3000,nthroot(3000,8.5))

10 Tage ago | 0

Answered
fsolve function give poor results for multiple equations
Your equations are linear, so there is no reason to be using fsolve. I was able to obtain the coefficient matrix A for your line...

10 Tage ago | 0

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Answered
Why do I only have an output of zeros for the 1 X 800
We cannot run your code, but a good debugging strategy would be to pause execution at this line, Kr_eff = ((1./mso).*sum(S.*(Ks...

10 Tage ago | 1

Answered
Nonlinear inequality in GA optimization with integer constraints
In the code you have shown for POWER_CONSTRAINT(~), it does not make sense that POWER does not depend on the input, but rather o...

10 Tage ago | 0

Answered
I know how to divide my 256x256 image into 16x16 blocks using mat2cell. Now I want to access those 16x16 blocks successively to further divide them into 4x4 blocks.
Using mat2tiles https://www.mathworks.com/matlabcentral/fileexchange/35085-mat2tiles-divide-array-into-equal-sized-sub-arrays ...

10 Tage ago | 1

Answered
Generate a 100000x100000 matrix that takes less time and memory
Seems to me the whole code can be replaced by, function [a,ed] = Random_graph_genar_function(nodes, connectivity) a=logi...

10 Tage ago | 0

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Answered
Randomized Groups of Array
Ex. I have 250 numbers and I want them in 50 groups of 5 reshape( randperm(250) , 5,50) or 25 groups of 10, reshape( randpe...

11 Tage ago | 0

Answered
How to solve explicit equation of ellipse
If you convert the ellipse to its polar representation https://en.wikipedia.org/wiki/Ellipse#Polar_form_relative_to_center tha...

11 Tage ago | 1

Answered
How to find the solutions to a set of linear equations?
You can easily trap the point where NaNs are introduced using >>dbstop if naninf https://www.mathworks.com/help/matlab/ref/dbs...

12 Tage ago | 0

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