Community Profile # Bruno Luong

Last seen: Today Actif depuis 2009

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For loop over permutations of 1:n with very large n
If you don't care about finding optimal solution, why not just do n = 1e15; % 1e18 has problem of coding as in my comment above...

environ un mois il y a | 0

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find rows in a matrix where all the elements (of those rows) are not NaN
An alternative ways of testing a = [ NaN NaN NaN NaN NaN NaN NaN NaN NaN...

2 mois il y a | 0

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Inverse wavelet transform using only one wavelet transform
I guess because you feed in random data, the scale cannot by estimate correctly therefore the first level of the scale (and also...

2 mois il y a | 0

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try...catch for memory full error in imaq toolbox ?
To my knowledge there is no simple way to detect memory issue. What you ask MATLAB, e.g., using command such as [~,sys] = memo...

2 mois il y a | 0

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What could be a faster way to calculate first derivative of a field?
dfdt = (f(3:end)-f(1:end-2))*(1/(2*dt))

2 mois il y a | 0

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Merging piecewise polynomial (pp) structures
Using BSFK from this FEX https://www.mathworks.com/matlabcentral/answers/1810010-free-knot-spline-approximation-bsfk-problem?s_t...

2 mois il y a | 1

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How do you reshape an array to preserve the order in each row of the original array?
A = magic(3) reshape(A.', [],1)

2 mois il y a | 0

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3 subplots with the bottom one split in 2 vertically?
Plenty of examples are given in the doc page https://www.mathworks.com/help/matlab/ref/tiledlayout.html

2 mois il y a | 1

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Speeding up matrix operations
Instead of calling trapz, use matrix multiplication, and this probably beats anything out there in term of speed and memory A =...

2 mois il y a | 1

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Speeding up matrix operations
All loops are removed, but the memory requirement might be an issue. As I don't know what mean "very large N, M" I can't make a...

2 mois il y a | 0

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Construct a permutation matrix from two vectors
combinations, new stock function in R2023a a = [1 ; 2 ; 3]; b = [4 ; 5 ; 6]; combinations(a,b)

2 mois il y a | 1

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How to extract diagonal elements of multidimensional array ?
N = 7; A = rand(N,N,N,N,N); p=ndims(A); N=length(A); % Method 1: generalization of cyclist's answer step = polyval(ones...

2 mois il y a | 0

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How to avoid automatic conversion of complex to real?
Yes it works as intended, and no there is no way to disable it. This automatic conversion also affects the CPU and sometime it ...

3 mois il y a | 0

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Is it possible to solve the problem on a permutation set with MATLAB tools?
@potato curious I have function like f(x) = 4x₁+3x₂ and constraints like 3x₁+5x₂<=20, x₁+6x₂>=30. And need to find which permuta...

3 mois il y a | 0

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Question

xregion yregion back/front control
I play with the new xregion command (R2023A) The red region is hide by the histogram, not sure why it is not as document exampl...

3 mois il y a | 1 réponse | 0

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How to know interpolated points in a MATLAB plot?
% Dummy example of some curve that cross the horizontal line y=10 x = cumsum([0 rand(1,40)]); y = 12*sin(x); plot(x,y,'.-'); ...

3 mois il y a | 1

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minimum value optimization of matrix with constraints
Straighforward implementation, it seems more reliable than Matt's square-root parametrization. The square-root makes the gradie...

3 mois il y a | 0

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The most efficient way to calculate multiplication and summation of two large matrices
It is just a scaling of matrix multiplication, if you haven't recorgnize it A=rand(300,1000); B=rand(300,1000); tic C1=(A*...

3 mois il y a | 1

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Create random symmetric matrix with given cond number to pass it to pcg
n=10; % size of the system condtarget = 1000; % generate ransom spd matrix [Q,~]=qr(randn(n)); r = rand(n,1); r = (r-min(...

3 mois il y a | 0

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How to get a smooth plot by filtering the sudden variation of the data?
It recovers a big tail part of the signal. Hard to guess what should be the signal at the begining. A=readmatrix('https://www.m...

3 mois il y a | 0

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FFT analysis with window of vibration during milling
I don't see the need of calling sgolayfilt. It is just a linear filter so it is equivalent to scale down the signal in frequency...

3 mois il y a | 0

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natural cubic spline interpolation of y-values: how to get derivative of the spline wrt the y-values?
The derivative f wrt to y_i is the spline interpolate b_i := (0,0,...,1,0...) where 1 is at ith position, since the spline is li...

3 mois il y a | 0

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natural cubic spline interpolation of y-values: how to get derivative of the spline wrt the y-values?

3 mois il y a | 0

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How to use isoutlier based in a part of the data?
Not sure, you are not better to describe what you want than most people; what you cann outlier seems to be point that violate th...

3 mois il y a | 0

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Modified Akima Interpolation process
Just look at the refernce provided in the doc page A New Method of Interpolation and Smooth Curve Fitting Based on Local Proced...

3 mois il y a | 0

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How to get around sparse row deletion for least squares calculation
I'm nit sure why you formalize as block sparse, since it is like solving d independent linear systems of the same size, and can ...

3 mois il y a | 0

Question

factorization of Multivariate polynomial
Hello, I want to factorize a multivariate polynomial in a complex field. I just don't understand why the result of this simple p...

3 mois il y a | 2 réponses | 0

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what is a reasonable step tolerance for optimization algorithms if parameters are in the range [0,1]?
Your question is not clear enough. the official doc explains how it eaxctly works https://www.mathworks.com/help/optim/ug/toler...

3 mois il y a | 0

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Matrix multiplication gives different result than manual dot products with each column
"Does anyone know why these two expressions don't give the same answer? " Why should they? The algorithm can perform diffrent s...

3 mois il y a | 0

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Why do I see a drop in the last datapoint (Nyquist frequency) of the spectra derived from pwelch?
No I beg to differ the answers that have given to you. The reason is the convention of onesided spectrum. In the code computepsd...

3 mois il y a | 0