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Bruno Luong


Last seen: Today Active since 2009

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Answered
Problem with solve() and "Empty sym: 0-by-1".
Your equations look illposed to me for three reasons* For a given j, LHS are known (4 x 1) vector Ax*Ax*B(:,j), let's call ...

15 hours ago | 0

Answered
Efficient Vectorization of For Loop
Not tested but the sign reading tell me M = 2*B' * (A.*C);

1 day ago | 1

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Answered
uicontrol doesn't work in Matlab 2023a
The button position you give is way off push the button outside the universe. This happens with all MATLAB. figure;pauseButton=...

2 days ago | 0

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Answered
Finding the index k of square nilpotent matrix A
This modified version of binary search only use matrix multiplication and keep track of A^2^p, p = 0,1,2 ...The number of matrix...

2 days ago | 0

Answered
Finding the index k of square nilpotent matrix A
I modify your original code and now it seems working: function k = nilIndex(A) [n,n]=size(A); l=0; k=n; B =A^l; while k-l>...

2 days ago | 0

Answered
When Should Generalized eig() Solver be Used for Ordinary eig() Problems?
Actually I think eig with 2 inputs is more approprite for multiple order eigen value and the degenerate case to non trivial jord...

3 days ago | 0

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Answered
uniform knot vector for splines
Your knot sequence seems NOT to be suitable for interpolation. The interpolation matrix is singular. x = linspace(1,6,6); xi =...

5 days ago | 0

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Answered
Strange behavior with ODE45 dependent on tspan
I would divide the time interval in three parts, as the typical time scales are different during the pulse and outside the pulse...

5 days ago | 0

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Answered
Matrix multiplication not returning on certain matrix content (Intel)
The matrix contains many non normalized floating point numbers and operations on these numbers are very slow; >> load('C:\Users...

7 days ago | 0

Answered
Using fmincon to solve objective function in integral form.
trapz(tspan/length(t), 2*x.^2 + 2*xd.^2) This looks wrong to me, you seem to assume t is equi distance (even in that case you s...

7 days ago | 1

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Answered
Lognormal distribution parameters mu and sigma
Is mu=log(mean) and sigma=log(Standard deviation)? No: https://en.wikipedia.org/wiki/Log-normal_distribution If X is log-norma...

8 days ago | 0

Answered
Effficient Computation of Matrix Gradient
The best N = 200; % 750 gradX_1 = zeros(N,N); w = rand(N,N); AXB = rand(N,N)+1i*rand(N); A = rand(N,N)+1i*rand(N); B = ran...

8 days ago | 0

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Answered
Effficient Computation of Matrix Gradient
I propose this, and time testing for N = 200; N = 200; % 750 gradX_1 = zeros(N,N); w = rand(N,N); AXB = rand(N,N)+1i*rand(N)...

8 days ago | 0

Answered
fmincon solution does not differ from initial guess if I provide gradient
To get more info turn the option 'CheckGradients' to 'on', and check the exitflag (third output) of fmincon

8 days ago | 1

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Answered
Function matchpairs does not work in MATLAB R2023a when I use a sparse cost matrix. Please help me out ASAP!
Your sparse matrix filled default cost wit 0 not 99. Then your expectation on that the result is identocal for different cost ma...

8 days ago | 0

Answered
error using spline: The first input must contain unique values.
Your spline command wouldn't do what you want, since for every x you have made corresponding two y values. It is NOT a function ...

8 days ago | 0

Answered
error using spline: The first input must contain unique values.
You did not post your spline command, my guess is you do spline(x,y) Try to remove the last (or the first value of th, then do ...

8 days ago | 0

Answered
How to fit a sine curve with only the maximum and minimum values
piecewise (co)sine interpolation (not fitting). I don't think you have extra DOF to play with if you restrict data to be local ...

9 days ago | 1

Answered
symmetric solutions of linear matrix equations
This is a method that use the small "original" linear system. I use pcg since it a linear solver that can accept function handle...

9 days ago | 1

Answered
symmetric solutions of linear matrix equations
If you have tthe optimization toolbox % Generate test matrices n = 3; A = randn(n); X=rand(n); X = X+X.'; B = X*A; % Add s...

10 days ago | 0

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Answered
how to multiply every single element in a matrix to entire of another matrix?
x = [100,500,900,1300,1700; 120,600,1080,1560,2040; 140,700,1260,1820,2380; 160,800,1440,2080,2720; 180,900,...

10 days ago | 1

Answered
symmetric solutions of linear matrix equations
% Generate test matrices n = 5; A = randn(n); X=rand(n); X = X+X.'; B = A*X; % Add small noise to B B = B + 1e-1*randn(siz...

11 days ago | 0

Answered
polyfit step by step or analytics
polyfit is the mfile you can step through in debugging mode. If you call with one outout argument (non normalized) it build van...

12 days ago | 0

Answered
Inserting 0 in sparse matrices without changing sparsity pattern?
Is it possible to tell MATLAB to not change the sparse matrix, but instead treat inserted zeros as any other value? Short answ...

12 days ago | 1

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Answered
How to fix my linear fit model?
Assuming you know where to split the data for left and right lines: x = [0 1 2 3 4 5 6 7 8 10 11 12 13 14 15 16 17 18 19 20 ......

12 days ago | 1

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Answered
How to fix my linear fit model?
This returns the piecewise linear function that is continuous at the break point. The correct break point is close to 18.6054 a...

14 days ago | 1

Answered
strcmp gives a 0 while it should be a 1
Look more carefully: There is a 'c' before '49' in A but not in B

15 days ago | 0

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Answered
Basic FFT Question: What range to sample the function in.
" However I am under the impression that the fft should not be sensitive to this change. " Your expectation in incorrect When y...

18 days ago | 0

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Answered
getfield to get values from an entire struct array?
Create 1 x 3 struct array with field named 'afield' s = struct('afield', {11 12 13}) s(1) s(2) s(3) % Here is the command t...

19 days ago | 0

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Answered
express basis spline derivative in terms of interpolation values
x = [1 2 3 4 5]; y = randn(size(x)); k = 5; f = spapi(k,x,y); B = spapi(k,x,eye(length(x))); fdd = fnder(f, 2); Bdd = ...

20 days ago | 0

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