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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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Answered
Rect function with Array
function [y] = rect(T0, A, t) y= ((t >= -T0/2) & (t <= T0/2)) * A; end

ongeveer 20 uur ago | 0

| accepted

Answered
Count the occurrence of each element in an array
string = 'I am happy'; [N,e]=histcounts(double(string),32:130); table(char(e(N>0)'),N(N>0)','VariableNames',{'Character','...

1 dag ago | 0

Answered
Why the outcome of my code is just white image?
Give imshow() a second argument to see the desired grayscale range. img1=im2gray(imread('cameraman.tif')); kernel = ones(3, ...

1 dag ago | 1

Submitted


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

1 dag ago | 1 download |

Answered
if and sum not working together
Because the sum cannot be done exactly in floating point. Therefore you need a tolerance, a = zeros(10,1)+0.001; b = sum(a) i...

2 dagen ago | 1

| accepted

Answered
what exactly norm(x) function do?
Assuming you only care about p=2, If you already have code that computes norm(x) for real x, you can extend it to complex x via,...

2 dagen ago | 0

Answered
Formula for norm(x)
Assuming you're only interested in p=2, if you already have code that computes norm(x) for real x, you can extend it to complex ...

2 dagen ago | 0

Answered
Multiple Image reconstruction with real and imaginary part in 2d array
What is the name of the variable stored inside the .mat files? If I assume it is X, then, a_real = load("img_real.mat").X; a_i...

3 dagen ago | 0

Answered
Equality between 2 floats not recognized when using <= relational operator
I feel pretty confident that either Money_types or Var2 is not truly equal to 0.05 in spite of what you suppose. It may appear t...

3 dagen ago | 0

Answered
Concatenate vectors stored in cell array
cell2mat( reshape( yourCell.' ,1,[],27) )

3 dagen ago | 1

Answered
Why ifft results of analytic signal spectrum don't match with theoretical time formula?
The IFFT and the continuous inverse Fourier transform are not the same thing. tau=0.4; t0=2.8; mag=10; Fs=200; dT=1/Fs; ...

3 dagen ago | 0

| accepted

Answered
Add constraints to intermediate variables in the process of using least squares to minimize the objective function to fit the parameters of the equation
With the constraints you mention, the problem does not fall within the scope of lsqnonlin. You will have to use fmincon, which a...

3 dagen ago | 0

| accepted

Answered
Trapezoidal rule with unevenly spaced data points
See trapz.

3 dagen ago | 0

Answered
regionprops Bounding box property returns values outside image dimensions
You should be comparing BoundingBox(1) with ImageSize(2) image = imread('https://www.mathworks.com/matlabcentral/answers/uploa...

3 dagen ago | 1

Answered
How do I graph a summation over an interval?
n=(0:10).'; fcn=@(x)sum( (2/3).^n .* cos(9.^n.*(pi.*x)) ); fplot(fcn,[-1,1]/10)

3 dagen ago | 1

| accepted

Answered
How to Vectorize this Code?
n3Array=normalize(n3Array,2,'n'); b0=b0/norm(b0); b0angles=acosd(n3Array*b0);

4 dagen ago | 0

| accepted

Answered
ScatteredInterpolant for Surface Extrapolation
The surface appears to be very well modeled by a Gaussian. An appropriate thing would therefore be to extrapolate using a Gaussi...

4 dagen ago | 0

| accepted

Answered
ScatteredInterpolant for Surface Extrapolation
[MAP_X,MAP_Y,MAP_Z]=readvars('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1131415/MATLAB.csv'); res=@(q)re...

4 dagen ago | 0

Answered
Using the output of one run of a function as the input of another iteration of that function
for i = 1:Counter List = ReduceArray(List); end

4 dagen ago | 0

Answered
How should we evaluate the similarity of two graphs?
I don't know why you think the MSE is "large", but perhaps the percent area difference would be more suitable to you: load elli...

4 dagen ago | 0

Answered
How to edit the name of a variable which is an object of a class?
This might be what you want. obj={GridSys1,GridSys2,GridSys3}; %list of objects [I,J]=find(A.*(1-eye(size(A)))); K=numel(...

5 dagen ago | 0

| accepted

Answered
Find max value in polyfit
xcrit=roots(polyder(q1)); %set derivatives to 0 xcrit(imag(xcrit)~=0)=[]; %get rid of non-real solutions zmax=max( polyva...

5 dagen ago | 0

Answered
How to do 4-D Equivalent of 3-D surface fitting ?
You can lsqcurvefit if you have Optimization Toolbox. If not, then you might be able to use fminsearch, if you have only a smal...

5 dagen ago | 0

Answered
How to use a trained neural network as objective function in fminsearch?
fminsearch.is unlikely to be able to handle 12 unknowns well. You should probably use fminunc if you have the Optimization Toolb...

5 dagen ago | 0

| accepted

Answered
How does the mod function compensate for floating point round off?
I suspect it is just meant to tell you that it doesn't do a naive computation like in modNaive below. m=1000*pi; n=pi; mod(...

5 dagen ago | 1

Answered
Plotting a triangle from 3 3x1 matrices
a = [5; 8; 13]; b = [-5; 7; 21]; c = [12; -32; 0]; V=num2cell([a,b,c,a],2); plot3(V{:},'-o', MarkerFace='r'); xlabel x; ...

6 dagen ago | 0

| accepted

Answered
If I renew my support contract can I download and install in new computer
The support contract is unrelated to the ability to install on additional machines. Most licenses entitle you to activate a Matl...

6 dagen ago | 0

Answered
Why fsurf show anything for my function?
You should normalize the function, so that the default MeshDensity works well. syms eta__2 zeta__2 Hvs2 =((230584300921369395...

6 dagen ago | 0

| accepted

Answered
How to find mean in theta-direction?
[theta,rho]=cart2pol(x,y); G=discretize(rho,___); %fill in the blank with desired binning specs zMean=splitapply(@mean,z(:...

6 dagen ago | 1

| accepted

Answered
Potential Bug? Freezing while making plots iteratively
Does the freeze always happen right before the saveas? If so, it might be worth issuing a drawnow() command right before the sa...

6 dagen ago | 1

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