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Matt J


Last seen: Today Active 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.

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Answered
Finding Transformation Matrix of a viewer3d object
I think the 3x4 camera projection matrix P would be, h=gca(); camz=h.CameraTarget-h.CameraPosition; camy=-h.CameraUpVector; ...

4 hours ago | 0

Answered
Uploading .mat files that contain nested structs into a datastore
This example shows how to use a fileDataStore to read partial data from a .mat file https://www.mathworks.com/help/matlab/ref/m...

5 hours ago | 0

Answered
Which optimization tool should be used for solving my convex optimization problem?
If, as you seem to, you have a non-quadratic (and therefore also nonlinear) convex objective function, then you must use fmincon...

9 hours ago | 0

Answered
Fixed-distance of legend outside plot axes
is there any "simple" parameter (i.e., not position) which controls the vertical distance between the legend box and the upper e...

12 hours ago | 0

Answered
the arc using the chord
Assume the chord is of length L and, with no loss of generality, assume also that it is aligned with the x-axis with end points ...

13 hours ago | 1

Answered
Dot Multiplication in MATLAB
For matrices A and B, the rule is generally that A.* B is element-by-element multiplication a(i,j).*b(i,j), which means that nor...

23 hours ago | 1

Answered
Find paths in graph that satisfy specific condition
s=[17,17,17,18,18,19,19,20,20,21,21,22,22,23,23,24,24,25,25,26,26,27,27,28,28,29,29,30,30]; t=[18,19,20,21,22,23,24,25,26,27,28...

1 day ago | 0

Answered
Getting error in fmincon with below code how to correct it
You seem to be trying to minimize over a space of functionals, F. You cannot do that with fmincon. The objective must be a funct...

1 day ago | 0

Answered
How to plot a grouped bar chart?
https://www.mathworks.com/help/matlab/ref/bar.html#bthxce9

1 day ago | 0

Answered
Subdivide a figure with a grid (as in Timescope)
Something like this, perhaps? t=tiledlayout(2,2); for i=1:4, nexttile(t), plot(rand(1,4)); grid on; end background=axes('Po...

1 day ago | 0

Answered
vectorized operations on symbolic functions
syms x1 x2 x3; % symbolic variables y = x1^3/3 + x2^2/2 - x3; % symbolic function y X = rand(500,3); % each row representing a...

1 day ago | 1

Answered
How to add an image to the current axes without replacing existing plots
You can use hold fcontour(@(x,y) (x-50).^2+(y-50).^2,[20,80],'m'); hold on imshow(imread('cameraman.tif')); hold off h=gc...

2 days ago | 0

Answered
Restart Fmincon Optimization from Checkpoint File
No, unfortunately. Restarting from the last point is probably the best you can do. Although, apart from the interior-point algor...

2 days ago | 0

| accepted

Answered
Image semantic segmentation dimension layer why not match input and output
Below is what analyzeNetwork gives. Only you know what you want the dimensions of each of your activation maps to be. Tell us at...

2 days ago | 0

Answered
Combining two arrays using a seconds order
number = randperm(10, 10) number2 = randperm(10, 10) I=ismember(number2,number(1:5)); number(1:5)=number2(I)

2 days ago | 0

| accepted

Answered
How can I calculate the unique centroids along with its radius range ?
load data; threshold=2; %Example input T=sortrows(table(Centroid, Radius),2) Centroid=T.Centroid; Radius=T.Radius; D=pdi...

2 days ago | 1

| accepted

Answered
Profile and debug load function
You could pursue your hypothesis by extracting the table from an object, then saving the idnlarx column to its own .mat file. Th...

2 days ago | 0

Answered
Struct field name with space or special character
Another option is to use dictionaries, which are a bit more similar to structs than tables, e.g. secretID=["Steve Rogers", "Ton...

3 days ago | 1

Answered
How do I mark all critical points on a graph of a function?
syms x; f=(sin(x)+(1/3)*(cos(5*x))); v=matlabFunction( diff(f) ); f=matlabFunction(f); x=linspace(0,2*pi,1e5); loc=find(g...

3 days ago | 1

| accepted

Answered
How do I add transparency to a plot in the Live Editor?
The syntax of giving an RGBA color setting seems to be a very old and undocumented feature, https://undocumentedmatlab.com/arti...

3 days ago | 1

Question


Plotting lines with quadruplets R-G-B-Alpha ?
It appears that in recent Matlab, I am able to append a 4th number to the RGB triplet, which appears to set either a transparenc...

3 days ago | 2 answers | 0

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answers

Answered
identifying and isolating consecutive numbers
code that will split A into B = [1 2 3 4] C = [14 15] D = [23 24 25] It would be a bad idea to split A into separate variables,...

4 days ago | 1

| accepted

Answered
Modifying the objective function in order to meet the optimization variable boundaries
If the boundaries are given by simple lower and upper bound vectors lb and ub, you can do, function fun=objective(A,lb,ub) ...

4 days ago | 0

Question


Where is dlfeval tracing information stored?
When dlfeval() is used to call a function, the computation is traced in such a way as to later allow automatic differentiation v...

5 days ago | 1 answer | 0

1

answer

Answered
3D image alignment: How to extract rotation angles about "static" x,y,z axes from a 3x3 rotation matrix
Attached is the utility that I use. In alignment with what you are pursuing, the code does assume the rotation matrix is a colum...

5 days ago | 0

Answered
Divide circular rings in N angular portions
The problem is that the angular portions do not have the same number of elements That's because the image is discretized into p...

5 days ago | 1

| accepted

Answered
Error in table row subscript
In what way is this not what you want? Northpopulation = readtable("LN_NEXTGROWTH.csv"); %LN = []; <-----You don't need this ...

5 days ago | 0

Answered
how can I plot a 3-D helical trajectory
t=linspace(0,18*pi, 3000); plot3(2*cos(t), 2*sin(t), t/pi)

5 days ago | 0

Answered
How to calculate spray cone angle?
load Image BW = imfill( bwareafilt(imclose(entropyfilt(im2gray(Image))>4.5,strel('disk',5)),1),'holes'); BW=bwareafilt(~im...

6 days ago | 1

Answered
Array indices must be positive integers or logical values.
fx = @(X) X.^2-1-sin(X);

6 days ago | 0

| accepted

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