Matt J

Last seen: Today

6.910 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
"Z must be a matrix, not a scalar or vector." PLEASE HELP!
You should have something like this: x1 = 1:.1:4; x2 = 1:.1:4; mesh(x1,x2, ps2func(x1,x2) ); grid on hold on functio...

alrededor de 4 horas ago | 0

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Answered
The the interpolate on the spherical coordinate system
I want to make a structure(eg: r=cos^10(theta)) in the spherical coordinate system and plot the combination of (orginal pattern+...

alrededor de 5 horas ago | 0

Answered
Index in position _ exceeds array bound when executing function, but not when running interactively
What's going on is size(draws,5)=1. You have passed in data whose dimensions are not what the code expects. This may be connecte...

alrededor de 6 horas ago | 0

Answered
How to add a plot to the structure array for each element
You can achieve what you want to use with subplot(), but I don't think it would be wise to give each time series its own axis. I...

alrededor de 19 horas ago | 0

Answered
BW consantred cell boundries
You'll find examples of how to do this kind of thing with alphashape() here, https://www.mathworks.com/help/matlab/ref/alphasha...

alrededor de 21 horas ago | 0

Answered
Vectorization or for loop (speedup)
Your vectorized code doesn't resemble at all what your for-looped code is computing. The vectorized implementation of your for-l...

1 día ago | 0

Answered
In nested for-loops, how and where should I set the counting index (indices?) correctly, for doing numerical root-finding using fsolve?
Well, first of all, you would not use fsolve when doing a gridded root search. In general, the search could be done like this: ...

1 día ago | 1

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Answered
Caclulate Horizonzal Area Between Two Curves And Minimize This Area (Optimization Problem)
EDIT: If you can accept the minimum squared area difference as a criterion, it has a known analytical solution, which is to take...

1 día ago | 0

Answered
how to find the right distance evaluation function of an ellipse
See this related thread, https://www.mathworks.com/matlabcentral/answers/555925-does-anyone-know-how-to-use-the-matlab-to-calcu...

1 día ago | 0

Answered
Plot a 2D image in projected coordinate systems.
I do not understand how a 3*10095 matrix is being interpreted as an image. You don't to have any pixel values, as far as I can s...

1 día ago | 0

Answered
Configure Matlab to use Python without pyenv
Mario's solution worked!

2 días ago | 0

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Answered
How to perform logical AND on intervals of contiguous locations
Using group1s from https://www.mathworks.com/matlabcentral/fileexchange/78008-group1s >> xg=group1s(x)+1; >> yg=splitapply(@a...

2 días ago | 0

Answered
How do you create a matrix of matrices?
Put your 10x10x10 arrays in cells https://www.mathworks.com/help/matlab/cell-arrays.html Example: >> A{3,3}=rand(10,10,10) ...

2 días ago | 0

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Question

Configure Matlab to use Python without pyenv
I am trying to call Python from Matlab R2019a on a Windows 10 PC. I have Python 3.7 installed under Spyder 3, but Matlab cannot ...

3 días ago | 1 answer | 1

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answer

Answered
Sub-matrix Access in a Square Pattern
Using mat2tiles from https://www.mathworks.com/matlabcentral/fileexchange/35085-mat2tiles-divide-array-into-equal-sized-sub-arr...

4 días ago | 0

Answered
Add for each element of a matrix the column vector in another dimension
Hi!i have a matrix 136*136. Call this A. This value is the index of a column of another matrix(24*391) Call this B. Then, re...

4 días ago | 1

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Answered
a 6x6 matrix with unkown x
See eig().

5 días ago | 0

Answered
local optimisation deterministic optimisation
fvalue = 50 is clearly a better (i.e. lower) objective value than 212.5, so there is every reason to believe that x1=42.5 x2=5...

5 días ago | 0

Answered
Failure in initial objective function evaluation. FMINUNC cannot continue. Need some help
You have set SpecifyObjectiveGradient=true, but your objective function code does not provide a second output for your gradient ...

5 días ago | 2

Answered
Does Matlab have an off-the-shelf function to generate a 2D circular convolution matrix?
You can use func2mat from https://www.mathworks.com/matlabcentral/fileexchange/44669-func2mat-convert-linear-function-to-matrix...

5 días ago | 0

Answered
Do numerical solutions depend on lower and upper bounds even when those bounds are not binded?
Changing the bounds affects where the algorithm can search, which can change the sequence of iterations, which can change which ...

5 días ago | 1

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Answered
What is considered good practice for coding up a function's derivatives, e.g. its Jacobian and Hessian matrices?
However, I imagine it's not best practice to continue doing this, especially when I start considering many more variables, and t...

5 días ago | 1

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Answered
How to compute cost function for fmincon?
r=[0.22 9.94 0.08; 0.16 0.95 0.08; 0.07 0.87 0.08]; R = [0.49; 0.42; 0.19]; omega=0.1; gamma=150; fun=@(x) norm( ...

6 días ago | 1

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Answered
Dividing 3D image to 3D patches
Using mat2tiles, https://www.mathworks.com/matlabcentral/fileexchange/35085-mat2tiles-divide-array-into-equal-sized-sub-arrays ...

7 días ago | 0

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Answered
How to apply Loop Function to this example
x=x0; for i=1:10 x=M*x; end

7 días ago | 0

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Answered
Question on GPU Computing
Make sure you have updated drivers and make sure you restart your computer after their installation. Then use gpuDevice() to sel...

7 días ago | 0

Answered
How to find the length of a curve from a list of points using different length scales?
curveLength = sum(vecnorm( diff( [x(:),y(:)] ) ,2,2))

7 días ago | 0

Answered
Creating matrix with other matrix
[a(:,2:3),b(:),c]

7 días ago | 0

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Answered
abcd is efghijk?
function C= circulant(x) n=length(x); C=zeros(n,n); C(1,:)=x; for i=2:n C(i, :)=[C(i-1, n) C(i-1,...

9 días ago | 1

Answered
parfor problem (broadcast variable)
There's never any gaurantee parfor will be faster, but I would modify the code as follows, B_Data=A_Data(:,2:5)/(0.6*2); B_ref...

9 días ago | 0