Community Profile

# Matt J

##### Last seen: Today
6,527 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

View details...

Contributions in
View by

matrix dimensions must agree error
Possibly a missing comma here, K=1/h^2*(2.*diag(ones(1,N+1))-diag(ones(1,N)-1)-diag(ones(1,N),1)); ...

3 hours ago | 0

| accepted

Define a variable without assigning a value
Perhaps you are trying to do symbolic computations, https://www.mathworks.com/help/symbolic/performing-symbolic-computations.ht...

9 hours ago | 0

Submitted

N-dimensional sparse arrays
Creates an N-dimensional sparse array object, for arbitrary N.

How can I use 'Least Squares Solver and Jacobian' instead of 'fminunc'?
Assuming D_d is the Jacobian of myfun, it would be, while (sum(abs(beta_u-beta_d))>0.1 && counter< 500) initial_gues...

1 day ago | 0

How to view centers on a 3D image
One suggestion is to use this FEX file to display the 3D volume with high transparency https://www.mathworks.com/matlabcentral/...

2 days ago | 0

Comparing the performance of colon, loop, and cell indexing
I checked that it is indeed the case with the Run & Time feature. I don't know what that is, but the better test in any case i...

4 days ago | 2

Using 'fminunc', I receive Optimization completed because the size of the gradient is less than the value of the optimality tolerance.
If the problem doesn't have a solution satisfying the tolerance condition in your while loop (sum(abs(beta_u-beta_d))<0.1) the...

4 days ago | 0

| accepted

Join table with different lengths
innerjoin(Grouped_Weight_position{i},Country)

4 days ago | 1

Replace array elements with another small array using indexing
b=strrep( strrep(a,[1 4 1],3) ,[3 4 1],2)

6 days ago | 0

Split values in an cell array by using a threshold
One way, A_lower = cellfun(@(x) x(x<threshold), A, 'uni',0); A_upper = cellfun(@(x) x(x>threshold), A, 'uni',0);

6 days ago | 0

| accepted

How to solve this equation z = c sqrt(x) ?
c=z/sqrt(x)

6 days ago | 0

Too many output argument error while using nested functions?
The code you've posted does not make it clear what problem you are encountering. There doesn't appear to be anything wrong in th...

6 days ago | 1

| accepted

How to multiply a scalar with matrix within loop and for each iteration store the values in new matrix?
There is no need for a loop: C=A.*reshape(b.^(0:n-1),1,1,[]);

6 days ago | 1

| accepted

Function lsqnonlin() has no optimization effect
And I have another question. My code has no optimization effect In this case, your initial guess already is optimal. You can se...

7 days ago | 0

Linear Extrapolation with interp2
The only remedy I can think of is to pre-pad the edges of the data V with linearly extrapolated values at distant X, Y. That way...

8 days ago | 0

overlaps() with only two polyshap objects
Use the two-argument form, Obstacles=[obstacle3 obstacle2]; criterion = sum( overlaps(car,Obstacles) ) == 1 ; %true if one a...

8 days ago | 0

| accepted

Constraints on meshgrid. Remove points outside function
Just apply logical indexing on the appropriate region and set it to NaN, bad=(y<s11(s2)) | (y>s12(s2)); z(bad)=nan;

9 days ago | 0

| accepted

How to run a curve approximation on a script using a function defined in a file and display the goodness of fit in a command window
You can't use the curve fit tool for a curve defined in an mfile. You can use lsqcurvefit, if you have the optimization toolbox,...

9 days ago | 0

| accepted

Parallel Processing with Multipul GPUs - fftn
You can use gpuDevice() to select different GPUs for different calculations. gpuArray commands run asynchronously without blocki...

9 days ago | 0

optimization based upon another optimization
You can write anything you want inside the code for your objective function, including other optimization processes. However, fm...

11 days ago | 0

Question

Finding handles to figure text
I am attempting to use findobj to retrieve text objects in a plot. For some reason, this fails (R2018a,b). In the following exam...

11 days ago | 1 answer | 0

### 1

fmincon nonlinear equality constraint
wopt = fmincon(NegPFMu, w0, [], [], Aeq, beq, lb,[], @(w) mycon(w, Cov, TargetVariance)); function [c, ceq] = mycon(w, Cov, T...

13 days ago | 1

| accepted

Uniformly distributed points generation inside quadrilateral with given points
I haven't used it, but this FEX tool claims to be able to do it: https://www.mathworks.com/matlabcentral/fileexchange/71398-ran...

13 days ago | 1

Fit a vector to matrix distribution
Can I just plug my new matrix into this and expect a distribution of values out for f1 and D1? I assume you already tried this ...

13 days ago | 0

Extract and show non zero pixels of a 2D image in MATLAB
The question seems very open ended. Perhaps as follows, spy(ima)

14 days ago | 0

How to get the coordinates of each room in a floor plan image through object identification method?
One approach is to close all of the doors morphologically: load('Walls') e=ones(1,105); A=imclose(imclose(~Image,e),e.');...

15 days ago | 0

| accepted

Submitted

Constrained minimum L1-norm solutions of linear equations
Finds least L1-norm solutions to linear equations C*x=d subject to linear and/or integer constraints.

How to get the coordinates of each room in a floor plan image through object identification method?
The Computer Vision Toolbox has a few corner detection routines, https://www.mathworks.com/help/vision/ref/detectharrisfeatures...

16 days ago | 0

Function name has to be same as file name?
When creating functions, aren't the functions supposed to have the same names as the file? No. If your mfile is a function file...

16 days ago | 0

| accepted