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Matt J


Last seen: Today
6,448 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

PLEASE NOTE: I do not read email sent through my author page. Please post questions about FEX submissions in their respective Comments section.

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Answered
Cells and Cell vectors help?
So, as a smaller example, if n=4 and the input is this C={ [1 2] , [], [2 3 4], [] }, the output should be this, A = 1...

9 hours ago | 0

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Answered
How to calculate from three points the "normal" at the second point
Once you have answered David's question, the attached function should be useful. It will find the normals to all the facets of a...

1 day ago | 1

Answered
Using Groups of Rows in a Parfor Loop
As mentioned in my comment, your example does not make it clear why a loop is necessary at all. However, the reason for your dif...

2 days ago | 0

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Answered
Help with non working for loop for generating a matrix
One approach is to write x,y, and A as matrix-valued anonymous functions of c, e.g., x=@(c)(4-c)./(6+c); y=@(c)10./(6+c); ...

4 days ago | 0

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Answered
Quadratically constrained linear maximisation problem: issues with fmincon
Well, it would be interesting to know what algorithm Gurobi uses, but the issue of the objective function difference appears to ...

5 days ago | 0

Answered
How can I create random Co-ordinate shifts (x,y,z) that add to a displacement of 1?
[a,b,c]=sph2cart(2*pi*rand,pi*rand,1);

5 days ago | 0

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Answered
How to constrain distance between points in optimization?
It can be set up this way, but keep in mind that this is a highly non-convex feasible set. It may be challenging to find a glob...

5 days ago | 1

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Answered
Multidimensional operations without for loop
Q=nan(8,n); [J,K]=ndgrid(1:8,1:n); I=maxloc(K); thetaIndices=sub2ind(size(theta), I,J,K); QIndices=sub2ind(...

8 days ago | 0

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Answered
fzero with function in matrix
syms x a=[sin(x),1;1,1]; b=[1/cos(x);1]; c=a*b; x=fzero( matlabFunction(c(1)-1) , pi/4 )

9 days ago | 0

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Answered
How can i speed up my code?
Please do not provide code in the form of embedded images. It prevents us from conveniently copy/pasting relevant sections. In ...

9 days ago | 0

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Answered
Get the diagonal without calculating the explicit matrix
Assuming B*C results in a square matrix, diagonal=sum(B.' .* C, 1);

9 days ago | 1

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Answered
Finding Area of Polygon defined by roipoly
roipoly returns a logical mask BW of the region BW = roipoly; so, its area in whole pixels would simply be area = sum(BW(:));...

9 days ago | 2

Answered
Setting nonlcon for fmincon / patternsearch as a matlabfunction
Create a wrapper function like the one below. To make it visible from the workspace where patternsearch is called, you can make ...

9 days ago | 1

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Answered
Use of kron with more than two matricies
One way would be to use my KronProd class https://www.mathworks.com/matlabcentral/fileexchange/25969-efficient-object-oriented-...

9 days ago | 1

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Answered
How to find a minimal number of rows in a sparse matrix to form a square sub-matrix for a given row?
If you have the Optimization Toolbox, you can try this linear programming solution: A = [ -1 1 0 0 0 0 ...

12 days ago | 0

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Answered
How to plot a single variable function with constraints
You can assign NaN to anything you don't want plotted. Example, x=linspace(0,2,1000); f=sin(x); f( 0.5<=x & x<=1)=nan; p...

14 days ago | 0

Answered
How to quickly find the column index of the last non-zero element in all rows in a sparse matrix?
[~,idx]=max(fliplr(logical(A)),[],2); result=size(A,2)+1-idx;

15 days ago | 0

Answered
Create n equidistant point along a circle
theta=linspace(0,360,n+1); theta(end)=[]; x=R*cosd(theta)+x0; y=R*sind(theta)+y0;

16 days ago | 0

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Answered
polyfit curve turns around near last point
Your data, when plotted alone, do not look very polynomial like. They do not even look like a function. x = [0 0 -0.0063 -0...

16 days ago | 0

Answered
How to quickly find the first non-zero element without iterations in all columns in a sparse matrix?
See this FEX submission, https://www.mathworks.com/matlabcentral/fileexchange/24641-vectorized-find-with-first-option

16 days ago | 0

Answered
How to quickly find the first non-zero element without iterations in all columns in a sparse matrix?
[~,result]=max(logical(A),[],1);

16 days ago | 0

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Answered
Use fsolve with an elliptic integral
It does not make sense to have a relational expression like, [K, E]== ellipke(m) as one of your equations, expecially one that...

17 days ago | 0

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Answered
Unclassified variables in a parfor loop
parfor i= 1:xyend-xystart+1 .... A = zeros(nx,ny); B = A; for n=1:Nn; for m=1:Mm; ...

18 days ago | 0

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Submitted


PROB2MATRICES: A selective version of prob2struct
Obtains matrices for select parts of an optimization problem from problem-based description.

19 days ago | 10 downloads |

Answered
Should I trust solutions obtained for a nonlinear non-transcendental equation in matlab using 'fzero' function?
fzero is a numerical root finder. One doesn't expect y(x) to be exactly zero at the roots that it finds, but it should be pretty...

19 days ago | 0

Answered
How to Put Objective and Constraints functions in the same function ?
I am working on an optimization problem with non linear inequality constraints and i wish to put the objective and constraints f...

19 days ago | 0

Answered
fmincon check gradients fail
CheckGradient uses central differences, whereas you appear to be using right handed differences. Are you certain that your const...

20 days ago | 0

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Answered
Minimising the summation of distance between two curves by placing the arc at best distance from origin
It's a non-differentiable, one dimensional cost function minimization. I would use fminbnd, https://www.mathworks.com/help/matl...

22 days ago | 0

Answered
Calling a class's static method from its metadata
or indeed a better way entirely from what I am proposing to achieve the calling of such an abstract static function on all subcl...

23 days ago | 0

Answered
How do I feed data from a non linear constraint function to the objective function when using fmincon?
Since your unknown vector is x, your objective and constraints must be functions of x and nothing else (except known constants w...

23 days ago | 0

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