Matt J

Last seen: Today | Active since 2009

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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.

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Can MATLAB do a 2-D FFT on a uniform parallelogram grid of measured points?
I need to Fourier Transform my parallelogram grid of measured values into ground freq domain, the Inv FT that into ground time d...

16 hours ago | 0

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How to find the point the graph crosses the x axis
x = @(t) (0.3) .* exp(-3 .*t) .* cos(4 .* t) + 0.2 .*exp(-3 .* t) .* sin(4 .* t); firstroot = fzero(x,[0,1]) %% graphs par...

1 day ago | 0

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After segmentation how to save number of subobejcts for each objects
If you mean you want to extract the sub-images forming the bounding box of each circle, then perhaps something like the followin...

1 day ago | 0

Answered
How to use fsolve to solve all the equations?
given too many results Perhaps you should use uniquetol, rather than unique.

2 days ago | 0

Answered
Controlling aspect ratio for tiled layout
[epsilon, phi,omega]=deal(rand(10), rand(10), rand(10,1)); tiles = tiledlayout(1,3); tiles.TileSpacing = 'loose'; ax1 = ...

3 days ago | 0

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Why does my matrix not change with each iteration?
I don't know why you think B should be changed by the loop when you generate it prior to the loop and never touch it again. Perh...

3 days ago | 0

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Optimization of Material Parameters
lsqcurvefit

4 days ago | 0

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Doc links no longer work
I experienced this and found it was because of name conflict between one of my user-authored mfiles and a MathWorks-authored mfi...

5 days ago | 0

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Can I run online a version different from the latest?
I don't think you can select an earlier Matlab version in Matlab Online.

5 days ago | 0

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Answered
How to customize the markers of the scatter figure, as shown below
Here's one way. Not sure you'll like the gymnastics that it requires: [x,y]=deal(rand(1,40), rand(1,40)); %scattered input dat...

5 days ago | 2

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Answered
Linear indices from colon operator
[I,J]=ndgrid(p1:p2,p3:p4); linear=sub2ind(size(array) , I,J);

5 days ago | 1

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Answered
Geometry properties in 3D (area, volume, moment of inertia...)
You can project your planar points into a 2D coordinate system and then use whatever 2D methods you had used previously to compu...

7 days ago | 0

Answered
Finding contiguous regions of interest in a mask and calculating the mean values of those regions when the mask is applied to an array
myImage=myImage'; L=L'; Lmax=max(L(:)); result=cell(1,Lmax); for i=1:Lmax result{i}=rasterMean(myImage(L==i...

7 days ago | 0

Answered
Handling missing observations while using fmincon
They should be zeros rather than NaNs, shouldn't they? With zeros, they will make no contribution to the linear part of the pred...

7 days ago | 0

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Filtering nose and removing spikes at local areas
Consider isoutlier.

10 days ago | 0

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Develop a generalize MATLAB code to * perform the following transformations on a pentagon defined by the points A, B, C, D, and E, where the coordinates are based on the last
Consider polyshape

10 days ago | 0

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I want the input of the neural network to be of data type 'SCB'
You haven't listed your Matlab version, but in newer versions, you are encouraged to be training with trainnet instead of trainN...

11 days ago | 0

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randomAffine3d is not properly random
EDITED: If you don't like what the default randomizer is doing, randomAffine3d() also let's you define your own, e.g., ori = [e...

12 days ago | 0

Answered
randomAffine3d is not properly random
If you want an isotropic distribution across the entire sphere, this should do it. ori = [eye(3);-eye(3)]; N=1000; o=cell(N...

12 days ago | 0

Answered
slow imwarp with large arrays
20k x 20k is an incredibly high resolution. Do you really need it, and if so, do you really need to use cubic interpolation, as ...

14 days ago | 0

Solved

Sum along each diagonal of a matrix
Write a routine that returns the sums along the diagonals of a given matrix, A, where the first diagonal is the bottom left corn...

15 days ago

Answered
Warning: Equation is badly conditioned. Remove repeated data points or try centering and scaling.
9th order polynomials do tend to be badly conditioned. Try using a lower order, or perhaps a spline model.

15 days ago | 0

Answered
help counting number of times a value occurs across matrix
values = [111, 112, 121, 122, 211, 212, 221, 222, 311, 312, 321, 322, 411, 412, 421, 422]; edges=[values,inf]; dp = [111 112...

15 days ago | 0

Problem

Sum along each diagonal of a matrix
Write a routine that returns the sums along the diagonals of a given matrix, A, where the first diagonal is the bottom left corn...

15 days ago | 0 | 9 solvers

Answered
Unable to achieve desired speed up using parfor
I find that all instances on B finish in about half the time as those on A. It baffles me... That is the expected result, assu...

19 days ago | 0

Solved

Sum All Positive Elements
Output a scalar that is equal to the sum of all positive elements in a given vector/matrix. For Example: The sum of all positi...

19 days ago

Solved

Build a block Toeplitz matrix
A symmetric block Toeplitz matrix has the form, where the are compatibly-sized matrices. Write a routi...

19 days ago

Answered
How to avoid unrecognized option names using optimget
Although I am using R2024a, that particular code still uses an older (2016-2019) version of lsqcurvefit. If so, problem solved....

19 days ago | 0

| accepted

Problem

Build a block Toeplitz matrix
A symmetric block Toeplitz matrix has the form, where the are compatibly-sized matrices. Write a routi...

19 days ago | 0 | 5 solvers

Answered
Finding the Center of Broken Vase Slices
You can use ellipticalFit() from this download, https://www.mathworks.com/matlabcentral/fileexchange/87584-object-oriented-tool...

19 days ago | 1

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