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Matt J


5.855 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
Question on Plotting from Cell Array
Points=reshape( [CellArray{:}] ,3,[],10); % for i=1:1000 X=Points(1,i,:); Y=Points(2,i,:); Z=Points(3,i,:)...

ongeveer 4 uur ago | 0

Answered
fsolve: How can I adress my variables to x(1)?
I don't understand your question very well, but maybe it will help to mention that fsolve does not require you to express the fu...

ongeveer 4 uur ago | 0

Answered
sum(c*b,'all')>sum(c)*sum(b)
Floating point discrepancies. You cannot count on floating point calculations giving a perfectly accurate result of 1 (unless th...

ongeveer 20 uur ago | 1

| accepted

Answered
Can an object pass a handle to itself?
Yes, you can pass an instance of A to the constructor of each child B. And, if A is a handle class, this will provide each child...

ongeveer 23 uur ago | 0

| accepted

Answered
Multiple ROI within one slice median calculation
I think this is what you want: I=reshape(Image,[],17); clear Medians for i=1:10 %loop over masks S=regionprops(ma...

ongeveer 23 uur ago | 0

Answered
to find 8 connectivity of an image
https://www.mathworks.com/help/images/ref/bwconncomp.html

1 dag ago | 0

Answered
covariance between the estimated parameters from curve fitting toolbox
There is lsqcurvefit in the Optimization Toolbox. However, the Curve Fitting Toolbox does let you return the Jacobian, which is ...

1 dag ago | 0

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Answered
fsolve found wrong solution for easy equation
Choosing an initial guess of x=0 in fsolve is often a bad idea because the gradient of the objective will frequently be zero the...

1 dag ago | 1

| accepted

Answered
emptying each row of matrix of a in a loop then uses respective matrices produced from it to get a certain value
Why not as follows, b=nan(size(a,1),1); %pre-allocate for i=1:size(a,1) tmp=a; tmp(i,:)=[], b(i)=...

2 dagen ago | 0

Answered
emptying each row of a matrix in a loop
a0=a; for i=1:size(a,1) a=a0; a(i,:)=[], end

2 dagen ago | 0

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Answered
fsolve found wrong solution for easy equation
fzero works better fun=@(x) x^2-1+a/b*log( (b*x^2 -a) / (b-a) ); [sol,fval]= fzero(fun,0) sol = -1.000000128628277 ...

2 dagen ago | 2

Answered
Returning an additional value that is not part of the fitness function or objective for all population evaluation in GA
function run_optimization allSigmas=[]; [xGA,fval] = ga(fun,nvars,[],[],[],[],lowbond,upbond,[],[],options); ...

2 dagen ago | 0

| accepted

Question


Implicit expansion with empty arrays
I was just idly curious why scalar expansion of an empty array seems to work here (R2018a), >> [1,2,3;4 5 6]-zeros(2,3,0) an...

3 dagen ago | 1 answer | 1

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answer

Answered
How to trim segments to fit a square
One solution is to use intersectionHull() from here https://www.mathworks.com/matlabcentral/fileexchange/30892-analyze-n-dimens...

3 dagen ago | 1

| accepted

Answered
extracting data from struct(structure within a structure)
This may be what you want, targets=[trials.target]; rows=vertcat(targets.row) but it is not very clear from your post how t...

3 dagen ago | 0

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Answered
ismembertol does not work as documented
The documentation isn't wrong. You've set a tolerance that can only satisfied reliably at A(6) in infinite precision arithmetic....

4 dagen ago | 0

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Answered
rotation constraint in imregtform
I don't have a clear picture of the "skips" you are refering to, but it vaguely sounds like it could be addressed by setting the...

4 dagen ago | 0

Answered
How to speed up function approximation?
There are a few inefficiencies that I see. Firstly, you shouldn't pick an arbitrary StartPoint like [0.8,0.8]. The problem can b...

5 dagen ago | 1

| accepted

Answered
Fit NonLinearLeastSquares to data and constrain curve to pass through point (0,1)
This answer incorporates Torsten's advice, but I also think you should re-formulate the model to make the exponential terms asym...

5 dagen ago | 0

Answered
Right-truncating a lognormal distribution
I think this is right. How can I code this? function out=conditionalCDF(a,b,x,beta,sigma) pa=normcdf(log(a)-x*beta,0,sig...

6 dagen ago | 1

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Answered
Coordinate system of matlab
However, i read that Matlab uses two types of coordinate systems which i find really frustrating and confusing at the same time....

6 dagen ago | 0

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Answered
How to find the area of the object in the center?
impoly worked pretty well for me. The area in pixels was 1358238 h=impoly(); area=numel(h.createMask) % 1358238

8 dagen ago | 1

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Answered
Plot feasible region of a high-dimensional linear programming along some dimensions
I tried to use this without success ... which stops with a long error message that I'm struggling to intepret. The error mess...

8 dagen ago | 0

Answered
Quadratic Programming (quadprog):
Using your posted A matrix I find that >> cond(H) ans = 7.5703e+18 For numerical purposes, this is a singular matrix ...

8 dagen ago | 0

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Answered
Increasing the bounds of integration on a strictly positive function decreases the result
A plot of the function reveals highly oscillatory behavior in the interval [-2e-6,0] which then flattens out to zero in [-1,-2e-...

8 dagen ago | 0

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Answered
Can multiple classes share external methods without inheritance?
Is it possible to have external methods that multiple classes share? It sounds like the "external methods" you are trying to im...

8 dagen ago | 1

Answered
How do I help quadprog converge?
Is checking that the constraints are satisfied and the optimality measure is low a good rule of thumb for making this decision? ...

9 dagen ago | 0

Answered
How to find mean line of the this edge?
Try bwskel

10 dagen ago | 0

Answered
Insert desired number of spaces in the string contains numerical value
How about txt="0 STR "+1

10 dagen ago | 0

Answered
Regression of a vector in a optimization problem
As the others have said, all regression routines in the Optimization Toolbox allow you to represent the unknown variable in vect...

11 dagen ago | 0

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