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Matt J


Last seen: Today
6.317 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
Constraining Function in fmincon
It sounds like you need to apply a nonlinear constraint. If so, you need to use fmincon with 9 or more input arguments specified...

25 Minuten ago | 0

Answered
how to create a symmetric Toeplitz matrix with bounds on eigenvalues?
R=fft(eye(400))/sqrt(400); e=zeros(1,400); e(2)=-10; e(end-1)=+10; e=ifftshift(e); T=(R'*diag(e)*R); T=real((T+T.')/2);...

3 Tage ago | 1

| accepted

Answered
optimization problem wont find any solutions
The problem is infeasible, or your initial guess x0 is too far from a feasible point.

3 Tage ago | 0

Answered
making coarse matrix from fine resolution matrix
A 3rd approach, more memory conserving and faster,. Z1=randi(100,8640,4320); u = 5; %upsampling factor d = 12; %...

4 Tage ago | 1

| accepted

Answered
3D image template matching by using (normalized) cross correlation?
I've never used it myself , but you could try this FEX submission, https://www.mathworks.com/matlabcentral/fileexchange/73946-n...

4 Tage ago | 0

| accepted

Answered
making coarse matrix from fine resolution matrix
If you have the Image Processing Toolbox, abc1=imresize(Z1,[3600,1800])

4 Tage ago | 1

Answered
find the element in matrix of intersecting vectors
attainedA=( max(a,[],1)==a ); attainedB=( max(b,[],2)==b ); result = c(attainedA & attainedB)

4 Tage ago | 1

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Answered
Quadprog message: The problem is non-convex
You cannot submit a problem that is borderline convex to quadprog if it is using an algorithm that expects convexity. If you do,...

4 Tage ago | 0

Answered
How to define a plane by matrices instead of a function?
For example, A = [104,122,111]; B = [253,122,153]; C = [104,124,111]; normal=normalize( cross(A-B,A-C),'norm'); %calcul...

5 Tage ago | 1

| accepted

Answered
When using the cftool, should I use Trust Region or Levenberg-Marquardt?
You can read here about the relative limitations of the 2 algorithms, https://www.mathworks.com/help/optim/ug/lsqcurvefit.html#...

5 Tage ago | 0

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Answered
Need Math to Rotate XYZ Point Around A-B Rotary Axes
See Rodrigues' formula, https://en.wikipedia.org/wiki/Rodrigues%27_rotation_formula Also, though you are apparently not worki...

5 Tage ago | 0

Answered
How to run fmincon using following function?
With no constraints, it would simply be, x=ones(200)/(-c*B);

6 Tage ago | 0

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Answered
No solution found when solving 3 non linear equations
A numerical sweep also gives evidence that there is no solution [x1,x2,x3]=ndgrid(linspace(-pi,+pi,512)); F1=cos(-x1+x2)+c...

6 Tage ago | 0

Answered
How do you call an inline or anonymous function within cellfun?
I reverted back to the for loop This might be faster than the for-loop, allB=[B{:}]; idx=ismember(allB,A); Blens=cellfun('l...

7 Tage ago | 1

Answered
How do you call an inline or anonymous function within cellfun?
But would still like to know how to use anonymous functions within cellfun There's no difference. Since findVal is already a fu...

7 Tage ago | 0

| accepted

Answered
Converged to an infeasible point.
The initial guess you have chosen x0 = [1,1,1,1,1,1,1,1]; seems very arbitrary. You should devise an initial guess more likely...

7 Tage ago | 0

| accepted

Answered
Matrix sequence manipulation for multiple value assignment
e=1:numel(A); lidx= any(idxes(:,1)<=e & e<=idxes(:,2),1); A(lidx)=1;

8 Tage ago | 0

Answered
Matrix sequence manipulation for multiple value assignment
If the intervals will always be disjoint, A=zeros(20,1); n=numel(A); A(idxes(:,1))=1; A(idxes(:,2)+1)=-1; A=cumsum(A(1:n)...

8 Tage ago | 0

Answered
Getting the coordinates of vertices of an A4 sheet with coins on it, for its further projective transformation and coin detection
The Computer Vision Toolbox has a few corner point detector apps, https://www.mathworks.com/help/vision/ug/point-feature-types....

8 Tage ago | 0

Answered
Relocate a value of a vector.
A=[1 2 3 4 5 6 7 8 9 0]; i=2; %position removed j=7; %target position B=A; k=i<j; B(i)=inf; C = [B(1:j+k-1),A(i),...

10 Tage ago | 2

| accepted

Answered
table less than operator
Are you sure you do not instead want to compare the content of a variable in the table to something?... yes this what I'm trying...

10 Tage ago | 0

Answered
Why is N not being displayed?
Because the loop condition is never satisfied and therefore nothing within it is ever executed. I think you meant to have, whil...

10 Tage ago | 0

| accepted

Answered
Displaying information about the data set by clicking on its plot and then show a value that is associated with the (x,y) point
.... set(dcm,'UpdateFcn',@(t,e) myupdatefcn(t,e,x,y) ); function txt = myupdatefcn(~,event,xdata,ydata) pos = get(eve...

10 Tage ago | 0

| accepted

Answered
Getting the linear portion of a non-linear curve
I'm not sure why a 2nd derivative test wouldn't have worked, as long as your points are noiseless: i=find( abs(diff(x,2))>somet...

10 Tage ago | 1

Answered
How to return the smallest vector.
If you "have them" in cell array form, then you could do something like this: >> vectors={[3 4 5],[1,2],[5 6 7 8]} vectors =...

11 Tage ago | 0

| accepted

Answered
a problem with setting fmincon options?
I would guess that you entered your options object as the 9th input argument to fmincon when it really should be the 10th. If yo...

11 Tage ago | 0

| accepted

Answered
set Precision in lsqcurvefit
You cannot do such a thing with lsqcurvefit. What you describe would require that you rewrite your objective function and bounds...

11 Tage ago | 2

Answered
Delete part of an image
[m,n]=size(oldImage); x=(1:n); y=(1:m).'; mask = (x-innerCenterX).^2+(y-innerCenterY).^2>=innerRadius^2 & ... (x...

11 Tage ago | 2

| accepted

Answered
Find the orientation of the skeletonized image
You can use houghlines to get the endpoints of all the line segments in the image. From that, you can easily calculate their slo...

11 Tage ago | 0

Answered
Using cell array to define Argument list in function Handle
That is not the right approach. You should be taking advantage of the fact that this is Matlab, and that your variables are allo...

12 Tage ago | 0

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