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Matt J


Last seen: Today
6 325 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
Unable to convert expression into double array
One way is to convert the symbolic expression to a function with matlabFunction. Then you can pass values to it as for any funct...

environ 17 heures ago | 0

Answered
Finding the matrix I generated two iterations back, while loop
One option is to maintain a list of the last two D's in a cell array: C = [0 0 0; 1 1 1;0 0 0]; B = [zeros(1, N); C; zeros(...

environ 18 heures ago | 0

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Answered
Newton's Method in Matlab
Did you check whether the while loop is ever executed, even once? I don't think it is.

environ 18 heures ago | 1

Answered
Constraining Function in fmincon
Now that the problem is clearer, it appears to me that you could have done the whole thing with linprog, f=[2,1]*t; Aineq = -...

environ 20 heures ago | 0

Answered
Upsampled image FFT contains NaNs.
You have a division by zero in this line, res = y./scale; That leads to NaNs in cp_vol and hence also in shift_vol.

environ 22 heures ago | 0

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Answered
Better parallelization than parfor?
The reason why I think it could be improved is that MATLAB tells me that vec in my above example is a 'broadcast' variable and m...

environ 22 heures ago | 0

Answered
Nonlinear Least Squares implementation
[x,resnorm,res,eflag,output1] = lsqnonlin(@(x) myLS(F, S0, r, w, t, Q0, x) ,x0) See also Passing Extra Parameters.

environ 22 heures ago | 1

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Answered
Returning an Entire Row Based on the Max in a Column
[~,imax]=max(x(:,2)); out = x(imax,:)

environ 22 heures ago | 0

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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...

environ 22 heures ago | 0

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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);...

4 jours ago | 1

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

4 jours ago | 0

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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; %...

5 jours ago | 1

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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...

5 jours ago | 0

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

5 jours 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)

5 jours 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,...

5 jours 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...

6 jours ago | 1

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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#...

6 jours 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...

6 jours ago | 0

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

7 jours 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...

7 jours 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...

8 jours 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...

8 jours ago | 0

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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...

8 jours ago | 0

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

9 jours 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)...

9 jours 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....

9 jours 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),...

11 jours ago | 2

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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...

11 jours 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...

11 jours ago | 0

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