Community Profile

photo

Matt J


Last seen: Today
7.860 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

PLEASE NOTE: I do not read email sent through my author page. Please post questions about FEX submissions in their respective Comments section.

Contact

Matt J's Badges

  • Personal Best Downloads Level 4
  • First Review
  • 5-Star Galaxy Level 5
  • First Submission
  • Master
  • Revival Level 4
  • 36 Month Streak
  • Thankful Level 4
  • Knowledgeable Level 4
  • First Answer

View details...

Contributions in
View by

Answered
Counting distinct elements in a vector?
numel(unique(A)) or max(findgroups(A))

circa 4 ore ago | 0

Answered
Too many output arguments while solving a constrained optimization problem.
You need, prob.solve(x0)

circa 5 ore ago | 0

Answered
How can I give a rotational velocity to spheres?
This uses AxelRot from the File Exchange (Download): figh = figure; %%Axes ax = axes('XLim',[-4 4],'YLim',[-4 4],'ZLim',[-4...

circa 8 ore ago | 0

| accepted

Answered
Can I speed up this matrix multiplication?
I have tried gpuArray, but it cannot be faster than normal Matlab * operation (maybe my GPU is not good enough..) Depending on...

circa 20 ore ago | 1

Answered
Can you organize scatter plot points?
This may be more along the lines of what you were originally looking for load Data; w=max( max(data,[],1) - min(data,[],...

1 giorno ago | 0

Answered
Is there a way to vectorise this vector/matrix product?
G=real( sum((R*W).*conj(W),1) );

1 giorno ago | 2

| accepted

Answered
Plot a best fit ellipse on a polar data set
Yes, it's possible, although the the quality of the fit will be affected by how clustered and how noisy your data is. For the fi...

1 giorno ago | 0

| accepted

Answered
How to sum the elements of a 4D matrix?
sum(yourMatrix,[1,2])

1 giorno ago | 0

Answered
How to Compute Cartesian to Polar If the ThetaZeroLocation on Top ?
x = -0.00781250; y = -9.593750000000000; t = 90-atan2d(y,x) %for theta

1 giorno ago | 0

Answered
Can you organize scatter plot points?
I think it may make more sense for you to move to a proper violin plot. With this 3rd party file, for example https://github.co...

2 giorni ago | 0

| accepted

Answered
Is there a way to extract the 4 corners points from all the points found with detectMinEigenFeatures?
If you have a binary map of the chequerboard, you can use imerode to separate the black squares and then pgonCorners https://ww...

2 giorni ago | 1

| accepted

Answered
sum of kronecker products
This solution is not completely free of loops (because of num2cell and cell2mat), but you can see below that it is still much fa...

2 giorni ago | 2

| accepted

Answered
how i can run least squares (LS) criterion algorithm on this data?
Maybe as follows, for i=1:size(x2,2) [c(:,i),flag,relres,iter,resvec(:,i),lsvec(:,i)] = lsqr(x1,x2(:,i),1e-4,70); end

2 giorni ago | 0

Answered
how can i avoid Nan in matlab expression and return 0
Here's a way you can do it by adding some additional binary variables and linear constraints. It requires that x be bounded to ...

2 giorni ago | 0

Answered
Pagemtimes accuracy versus for loop
I assume this is due to numerical deviations? Yes, there is no expectation that both approaches will produce the same floating ...

3 giorni ago | 0

Answered
Comma separated function output requests
I assume the reason for the behavior is so that wrapper functions can have the same default outputs as the functions they are wr...

3 giorni ago | 0

Question


Comma separated function output requests
The comma separated list expression A{1:0} generally produces an empty result, e.g., A={1,2,3}; [A{1:0}] Therefore, I might e...

3 giorni ago | 3 answers | 2

3

answers

Answered
how can i avoid Nan in matlab expression and return 0
Replace sqrt(x.^2)./x with sign(x)

4 giorni ago | 0

Answered
How to protect arbitrary variable names
Since these functions often end up nested inside other functions I can't tell here if you genuinely mean the functions are "nes...

4 giorni ago | 1

Answered
Fix dynamically named variables
Vartable.Properties.VariableNames=extractBefore( Vartable.Properties.VariableNames, '_');

5 giorni ago | 0

| accepted

Answered
Point of intersection of two functions
Find the root of the difference between the functions using fzero().

5 giorni ago | 0

Answered
Fit a plane on 3D-point data, orthagonal to an existing plane?
I think if you want to do this properly, the Curve Fitting Toolbox won't be enough. You really need to jointly fit both Data set...

5 giorni ago | 0

| accepted

Answered
I am getting NaN values after some iterations in my loop
To find out where they are first introduced, you can use, >> dbstop if naninf

5 giorni ago | 0

Answered
How to call objective function in outputfcn or plotfcn during optimization?
Unfortunately the fields in optimValues do not contain the obj_function It does. It's the fval field. https://www.mathworks.co...

5 giorni ago | 0

| accepted

Answered
Fasten the speed of assigning values to a large tensor
You can save some time if you pre-allocate the array: % Simple example M = 400; n = 10; tic A = ndSparse.spalloc([M,...

5 giorni ago | 0

Answered
Optimization of nested "for" loops
Replace the loop with, x=X(:)-X(:).'; y=Y(:)-Y(:).'; xsq=x.^2; ysq=y.^2; xysq= xsq+ysq; tmp1=xysq + e^2; PH...

5 giorni ago | 0

Answered
No feasible solution found. How to fix it
You have provided equality constraints that have no solutions, as can be seen by: rank(Qeq) rank([Qeq,b.'])

6 giorni ago | 1

| accepted

Answered
Using unique-function to add up values
Possibly faster: totals = splitapply(@sum, DiffTime, findgroups(Location))

6 giorni ago | 0

Answered
Using unique-function to add up values
accumarray(ic, DiffTime)

6 giorni ago | 2

| accepted

Submitted


Further tools for analyzing objects in N-dimensional images
A collection of tools to supplement bwpropfilt, bwareaopen, and the like.

7 giorni ago | 9 downloads |

Load more