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Matt J


5,364 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
do not regress if any Y is zero
How about c = regress(y(y~=0), x(y~=0));

5 hours ago | 1

Answered
How to set elements of a matrix to 0 from one index to the remaining of the row ?
[I,J,S]=find(X); keep=(J<Column_Index(I)); X=sparse(I(keep), J(keep), S(keep) ,m,n);

21 hours ago | 1

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Answered
Using scatteredInterpolant for 1-D data
These FEX files look applicable (and popular): https://www.mathworks.com/matlabcentral/fileexchange/22441-curve-intersections ...

23 hours ago | 0

Answered
fft definition in matlab doc puzzling
Given that the fft results in both positive and negative frequencies, I woumld have guess a defintion like : Perhaps a better w...

1 day ago | 0

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Answered
Can I avoid this broadcast variable?
Why not this? parfor k = 1:size(S,2) tmp=S(:,k); for j = 1:length(b) fun(tmp,b(j)); end end

1 day ago | 0

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Answered
how can I transform this code into a for loop
a=[0.1, 0.3, 0.6, 1.3, 1.6, 1.9, 2.2, 2.5, 2.8]; b=a+0.25; for i=1:9 subplot(3,3,i); [S,f]=myFFT( x...

2 days ago | 0

Answered
Find the index of the elements that are between two radii
Perhaps this is what you want? G=discretize(Final_r,initial_r); Indices = accumarray(G.',(1:numel(Final_r)).',[],@(z) {so...

2 days ago | 0

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Answered
Find clusters with specific value in 3D matrix
S=regionprops(yourImage<0.05,'Area','PixelIdxList'); S=S([S.Area]>=30); %edited result=zeros(size(yourImage)); for i=1:nu...

2 days ago | 1

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Answered
Find the index of the elements that are between two radii
index = (Final_r>=initial_r) & (Final_r<[initial_r(2:end),inf])

2 days ago | 0

Answered
non overlapping random circles
Perhaps one of these FEX contributions would be helpful.

3 days ago | 0

Answered
Undefined function or variable 'drawellipse'
drawellipse wasn't introduced until R2018b.

3 days ago | 1

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Answered
Product of elements in an array
For example, >> x=[3 5 7 11]; >> prod(nchoosek(x,3),2) ans = 105 165 231 385

3 days ago | 0

Answered
How to find the coordinates of the white square ?
Some simple morphological operations are all you need. A=imbinarize((imread('image.jpeg'))); A=bwareafilt( imopen(A,strel...

3 days ago | 0

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Answered
Calculating dot product of 2 3 dimensional row vectors
I think this is what you want: x=input('Enter the 1st pair of 3 vector elements in [square brackets]: '); if (numel(x)~=3); ...

3 days ago | 0

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Answered
issorted alternative for optimization toolbox
You can do, prob.Constraints.sorted = ( A(2:end) <= A(1:end-1) );

3 days ago | 0

Answered
The "fslove function" got different answer on two computers
Have you checked whether both results are valid solutions to the equations? If a continuum of solutions exists, it is quite conc...

3 days ago | 1

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Answered
fft definition in matlab doc puzzling
Your second definition only makes sense if you define the indexing in Y(k) to be modulo-n. Otherwise, it is not clear what it me...

4 days ago | 0

Answered
How to fix this error in interpolation?
interp1 is complaining that y3 has repeated elements. They are required to be unique and monotonic.

4 days ago | 0

Answered
How to sum multiple matrice in loop ?
Is this what you want? result = squeeze(sum(T3,3)); If not please clarify what the dimensions of the final result should be.

4 days ago | 0

Answered
Imprecision problem: pinv(H) is not equal to pinv(H'*H)*H'
Seems to me the obvious solution is not to push gamma to infinity. That removes the regularization whose purpose is precisely to...

4 days ago | 0

Answered
Outer product of two rectangular matrices
outer = r(:)*r(:).'

4 days ago | 0

Answered
Using other solvers for models generated by optimproblem
You can use prob2struct to help convert a problem-based description of the linear constraints to the matrices required by other ...

5 days ago | 2

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Answered
Plotting shapes based on equations and weights.
For 2D and 3D functions, you can use fimplict and fimplicit3, e.g., fimplicit(@(x,y) w0+w1*x+w2*y)

5 days ago | 0

Answered
What is the equivalent of the function 'wait' after using 'imellipse' for the new function 'drawcircle' (version R2018b)?
Here's a (ch)easy workaround using the waitfordoubleclick.m file attached drawcircle; waitfordoubleclick You may have to adjus...

5 days ago | 0

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Answered
Multiple regression with multiple variations
e=ones(size(x1)); abcdef = y/[e;x2;x3;1./x1;x2./x1;x3./x1] abcdef = 6.3301 0.0113 -0.0117 88.7676 -0.8784...

7 days ago | 0

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Answered
assigning a variable to an output of a function at a certain time
t=1; yone=yourFunction(t);

7 days ago | 0

Answered
Linear and Non-Linear constraint Optimization
Yes, c and ceq can be vectors (or matrices, or arrays of any dimension...).

7 days ago | 0

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Answered
Specifying some but not all Nonlinear Constraint Gradients through Fmincon
I agree, it would be nice if the Optimization Toolbox would expose its finite differencing code as a separate function, so that ...

8 days ago | 0

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Answered
innerjoin invalid parameter name
It appears that you are attempting to do the following: Akeys={'DateAnnounced','TargetName','AcquirorName'}; Bkeys={'DateAnnou...

8 days ago | 0

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Answered
How to Show 1/4 in 1/2^2?
You can also create symbolic numbers sym(1/3) 1/3 but be mindful that all calculations you do with such numbers will also giv...

8 days ago | 1

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