# Matt J

Professional Interests: medical image processing, optimization algorithms

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**Content Feed**

Surface plot error for Z must be a matrix, not a scalar or vector

Just don't know how to make z a matrix after sph2cart z will be a matrix if at least one of the inputs f, theta and phi are mat...

ongeveer 4 uur ago | 0

Why is my plot linear when the anonymous function z is clearly nonlinear?

It simply looks linear because you are plotting it over too narrow a range. Req = 0:120000; plot(Req,z(Req));

ongeveer 5 uur ago | 2

| accepted

Transpose for double integral

To perform the double integral, f(x,y) needs to be calculated at all combinations of x(i) and y(j). The transpose makes x a colu...

ongeveer 12 uur ago | 0

How to load variables from Excel into Matlab workspace?

if you have many columns of data to load, you would not put them in separate workspace variables. You would just read them into ...

ongeveer 20 uur ago | 1

Compute Volume of Cubic element from coordinate

One way: [~,volume(i)]=convhull( Coordinate(Element(i,:),:));

1 dag ago | 0

Solve taking too long, how to optimize code?

Well, one solution is clearly, T1=T2=T3=T4=T5=(Tsurr-273) as you can verify by direct subsitution.

1 dag ago | 0

what changes should i make in final optimised value with opt time vector

Use prob2struct s=prob2struct(prob); s.f0 The value of s.f0 will be the discrepancy between a problem-based linear optimizati...

1 dag ago | 0

fminunc giving correct optimized values for anonymously defined function, BUT wrong value for .m function

At same initial values in two cases (anonymous function and .m function) the objective function gives same values which means th...

1 dag ago | 0

How do I create a matrix that has as values the averages of variables found in loops?

If that's all you want to do, you shouldn't be saving the coordinates of the ROIs. You should just create a binary mask BW of ea...

3 dagen ago | 1

| accepted

How to assign a specific values to the nearest X,Y point

V=interp2(LON,LAT,SSP,X,Y,'nearest'); See also griddedInterpolant.

4 dagen ago | 0

I am trying to compute the zero of a function using fzero, but the system always says my function must be finite and real. How can I solve that? Thank you!

Clearly, your function is non-finite at x=0. There is a factor of x^2 in its denominator. Regardless, fzero() is the wrong too...

4 dagen ago | 0

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Loop in a cell array that consist of matrices in each cell

Easier: results=cat(3,results{:}); max_column = squeeze( max(results(2:end,12,:)) )

4 dagen ago | 0

Loop in a cell array that consist of matrices in each cell

You have a variable called "max" previously defined in your workspace.

4 dagen ago | 0

I would like a function to remove the duplicate values, but one that removes the duplicate value as well.

USing the functions in https://www.mathworks.com/matlabcentral/fileexchange/78008-tools-for-processing-consecutive-repetitions-...

4 dagen ago | 0

| accepted

fminunc crashes matlab if large number of input variables used

Well, the practice you have of cumulatively nesting anonymous functions inside one another is asking for trouble. You should at ...

4 dagen ago | 1

| accepted

How to apply logical matrix to the matrix with array operation?

Matrix = [ 3 4; 5 6]; Logical= [ 1 1 ; 0 0]; R=Logical.*Matrix

5 dagen ago | 0

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How to substitute one value in vector by vector?

x=[-1 1 -1 1]; X=kron(-x,[1,2,3]); X=X+4*(X<0)

5 dagen ago | 0

How to substitute one value in vector by vector?

x=[-1 1 -1 1]; x=strrep(10*x,10,[3,2,1]); x=strrep(x,-10,[1,2,3])

5 dagen ago | 0

why the caculation results is different for parfor-loop and for-loop?

Probably because, with a parpool active, the matrix multiplication code cannot multithread the operation in precisely the same w...

5 dagen ago | 1

Is there any exmaple on how to apply fmincon function to a state space optimisation problem?

These should be applicable, https://www.mathworks.com/help/optim/ug/fit-ode-problem-based-least-squares.html https://www.mathw...

5 dagen ago | 0

How to substitute one value in vector by vector?

x=[-1 1 -1 1]; i=(x+3)/2; V=[1 2 3;3 2 1].'; X=reshape( V(:,i) ,1,[])

5 dagen ago | 0

How to substitute one value in vector by vector?

x=[-1 1 -1 1]; idx=(x==1); X=nan(3,numel(x)); X(1,idx)=3; X(2,idx)=2; X(3,idx)=1; X(:,~idx)=4-X(:,idx); X=X(:)....

5 dagen ago | 0

Calculation of Hessian matrix in gamultiobj hybrid function

If you mean that you can't compute the Hessian yourself and wish to do so using finite difference approximations then https://w...

5 dagen ago | 0

Finding the average of the neighbors of each pixel in an image

mean4=conv2(image,[0 1 0; 1 1 1; 0 1 0]/5,'same'); mean8=conv2(image,ones(3)/9,'same');

5 dagen ago | 1

Issue while fitting semi-circle on a set of points

See incircle() in https://www.mathworks.com/matlabcentral/fileexchange/34767-a-suite-of-minimal-bounding-objects?s_tid=srchtitl...

5 dagen ago | 0

Issue while fitting semi-circle on a set of points

I recommend circularFit from https://www.mathworks.com/matlabcentral/fileexchange/87584-object-oriented-tools-for-fitting-conic...

5 dagen ago | 0

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Using a loop to impose specific values

For example, x=linspace(-1,1,1000); plot(x,twoparts(x)) function y=twoparts(x) y=abs(x); region=x>0; y(region)=x...

5 dagen ago | 0

combining results into a single matrix

One way. h = [1 2 3 4 5]; n=numel(h); m=n-2; First_Matrix=toeplitz([1,zeros(1,m-1)] ,[1 1 1 zeros(1,n-3)]).*h

6 dagen ago | 0

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How do a cell2mat conversion for a non-uniform cell to a matrix

cell2mat(DD(:))

6 dagen ago | 0