Matt J

Last seen: Today

6,896 2009 年以降の合計貢献数

Professional Interests: medical image processing, optimization algorithms

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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...

1日前 | 0

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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...

1日前 | 1

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

1日前 | 0

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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...

2日前 | 0

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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 ...

2日前 | 2

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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...

2日前 | 0

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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 ...

2日前 | 1

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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...

3日前 | 1

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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( ...

3日前 | 1

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

4日前 | 0

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

4日前 | 0

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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...

4日前 | 0

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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))

4日前 | 0

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

4日前 | 0

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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,...

6日前 | 1

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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...

6日前 | 0

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Use inpolygon command for multiple polygon areas
Use discretize(), https://www.mathworks.com/help/matlab/ref/double.discretize.html Apply it separately to all of your xv's and...

6日前 | 0

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For loop and array type
Best guess - your loop has reached a z for which allcsvfiles{z,1}(:,4) contains text. Use dbstop() to check.

6日前 | 0

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Array of Structures (not structure array)
I don't know if this is something you explored in (2), but if so, I don't see why it wouldn't cover what you are trying to do. ...

6日前 | 0

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Memory cost of multiplying sparse matrices
Here's another customized multiplication routine for tall A. I do not know how it compares to Bruno's in terms of speed, but it ...

8日前 | 0

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Memory cost of multiplying sparse matrices
I believe it is simply because Matlab sparse matrix routines don't handle very tall & thin matrix dimensions very well. It beco...

9日前 | 0

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質問

Convert a string array to a cell array of strings
Starting with a cell array of strings, >> C={'person','woman','man','camera','TV'}; I know that it is possible to convert to ...

9日前 | 1 件の回答 | 0

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Splitting a binary image into 2 parts
There is a small break in the curve which I assumed was supposed to indicate the desired dividing point between the right and le...

10日前 | 0

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Plotting 3D network of points and their error ellipsoids
You can use scatter3() to plot the points and ellipsoid() to overlay ellipsoids around them. https://www.mathworks.com/help/mat...

10日前 | 0

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fminsearch for existing simulation
As Walter said, fminsearch does not know or care how many lines of code are used to implement your objective function. Bear in m...

10日前 | 0

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How to set 2 constrain bounds at the same time?
lb=[-10,-30]; ub=[+10,+30];

10日前 | 0

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Is convhulln function work for N dimensional
The points you are inputting to convhulln do not form a solid shape in R^5. To within numerical precision, they all lie on a lin...

10日前 | 0

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Sum each page of a 3D matrix and append sums as rows of new 2D matrix
D=permute(sum(C,1),[3,2,1])

10日前 | 1

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Intlinprog function - problem
The optimal solution of a linear program can be discontinuous as a function of the problem data, particular when you have intege...

11日前 | 1

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matrix manipulation and transposing
Because when v is a column vector and theta is a row vector, you get implicit expansion, https://blogs.mathworks.com/loren/2016...

11日前 | 0