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Matt J


Last seen: Today
6 310 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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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...

environ 15 heures ago | 1

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#...

environ 17 heures ago | 0

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...

environ 17 heures ago | 0

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

1 jour ago | 0

| accepted

Answered
Fsolve function does not solve a nonlinear system with complex conjugation.
Some relevant reading, https://www.mathworks.com/help/optim/ug/complex-numbers-in-optimization-toolbox-solvers.html

1 jour ago | 0

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...

1 jour 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...

2 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...

2 jours 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...

3 jours 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;

3 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)...

3 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....

3 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),...

6 jours 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...

6 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...

6 jours 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...

6 jours 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...

6 jours 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 =...

6 jours 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...

6 jours 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...

7 jours 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...

7 jours 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...

7 jours 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...

8 jours ago | 0

Answered
Divide plane into two separate planes
Let b1 and b2 be basis vectors for the plane and let x0 be a point in the plane. Then, for example, x0(:) + b1(:)*randn(1,N) + ...

8 jours ago | 0

Answered
how to plot values that only fall within a range?
KPH_70 = mean(Y(FVY)); yyaxis left plot(X(FVY),Y(FVY)); yyaxis right plot(X(FVY),KPH_70*ones(size(FVY)));

8 jours ago | 0

| accepted

Answered
How to pass a vector to a function that creates matrix
>> b=[1 2 3]*10; >> T=@(i) [b(i)+9 , 8 ; 8 , 7 ]; >> T(3) ans = 39 8 8 7

8 jours ago | 0

Answered
how to calculate direction in rotated coordinate system
Using AxelRot (Download), and assuming all angles are given in radians, [x,y,z] = sph2cart(Azi_Old,Elev_Old,1); P=AxelRot( ...

8 jours ago | 0

Answered
How to work with Nelder-Mead algorithm with 7 unknown variables?
You can use fminsearch (an implementation of Nelder-Mead) with any number of variables. However, there is no way to gaurantee th...

9 jours ago | 2

Answered
f(x)=sin(x)-x^5=0 providing x is not equals 0 ,function in the interval x [0,3]
>> [x0,fval]=fzero(@(x)sin(x)-x.^5,[0.8,1]) x0 = 0.9610 fval = -1.1102e-16

9 jours ago | 0

| accepted

Answered
Generating Toeplitz Matrix which Matches the Convolution Shape Same
Using interpMatrix (Download), nH=numel(vH); nX=numel(vX); ic=ceil( (nH+1)/2); mH = interpMatrix(vH,ic , nX,1);

9 jours ago | 0

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