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# Bruno Luong

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1,567 total contributions since 2009

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Shortest path in a 2d matrix
%W=[ 1 2 3; % 4 5 6; % 7 8 9 ] W = randi(9,5,5) % Build the 4-connected graph [m, n] = size(W); [i, j] = ndgrid(1:m,1:n)...

6 hours ago | 1

Selecting a "random" element from an array with each element having it's own weighting
A=[1,2,3,4]; p=[10 20 30 40]; c=cumsum(p); [~,r]=histc(rand(1,1e6),[0 c/c(end)]); % generate 1e6 numbers r=A(r); % Chec...

15 hours ago | 1

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A QR complexity question
The O(n^3) is number of flops, which is not proportional to tic/toc. You time also RANDN Calling QR has overhead that is signi...

1 day ago | 2

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How to Solve this Big System of Equations
Possible causes: your matrix is wrongly constructed you forget to include proper boundary conditions you forget to add condit...

1 day ago | 1

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fill matrix with all options of successive, increasing numbers 1-5
p = 5; n = 12; j = nchoosek(2:n,p-1); m = size(j,1); % == nchoosek(n-1,p-1) == 330 and not 96 i = repmat((1:m)',1,p-1); A...

1 day ago | 1

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How do I find a D matrix that satisfies [K]*inv(M)*[D]==[D]*inv(M)*[K] ?
You have homogeneous linear equation, the entire null space of operator (D considered as input) K*inv(M)*D-D*inv(M)*K (dimensi...

2 days ago | 1

Remove overlapping intervals from two array intervals without using a loop
You might interest to use my interval-merging FEX

3 days ago | 0

Plotting a smooth curve from points
Direct analytic method using piecewise cublic polynomial. The curve is first-order differentiable, but not second order differen...

3 days ago | 1

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Plotting a smooth curve from points
No extra points needed (but you might add to twist the shape of the curve in the first and last interval), Spline order >= 8th ...

4 days ago | 1

How to calculate the volume enclosed by a set of XYZ points in 3D?
V is the volume between the plane x-y (z==0) and the surface z(x,y) from your data. If you want the volume of the data after su...

4 days ago | 1

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How to triangulate a non-convex ordered set of points?
I recommednd this Mesh2D FEX

4 days ago | 0

Vectorizing issue in MATLAB
It is in general not possible to vectorize sequential calculation like yours.

6 days ago | 0

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How to find out a smallest sub-matrix B from a sparse matrix A which has the equal rank and # of non-zero columns?
Done, B=A (so all rows of A) meets your requirement >> A = [ 1 -1 0 0 0 0 0 0 0 1 ...

7 days ago | 0

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Converting a 3D Matrix to multiple 2D matrices
Assuming A is array 1000 x 1000 x 40 C = num2cell(A,[1 2]);

10 days ago | 1

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Multiply all pages of a matrix
AFAIK there is no alternative way in general; unless your matrices has special property that can use some simplification.

12 days ago | 0

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I can't see addpath in your snip of code. When you compile the app, all the source mfiles used by you app MUST be found by depe...

12 days ago | 0

Matlab interpolation between two surfaces
Assuming your two original surfaces are z1 and z2, juts pick w scalar in (0,1) interval, zinterp = (1-w)*z1 + w*z2; If w == 0 ...

12 days ago | 0

Matlab executable not running on remote access files
"I would like to change the directories for reading and writing theses files." IIRC the cd command is non effective in deployed...

12 days ago | 0

Question

Answers editor seems to be broken
I can't see the editor tool in some PC display config + Firefox After a simple view of the thread it ask me as if I would edit ...

13 days ago | 1 answer | 0

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Question

Is FORMAT DEBUG still any useful?
Can someone has an explanation for this (R2020B) clear clc x=1; y=x; x=x+1; format debug y x that produces y = ...

14 days ago | 1 answer | 1

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Two linear equation with absolute value equation
Correct minimum norm solution is xmin = 90.0000 -40.0000 5.0000 5.0000 normxmin = 98.7421 obtain...

14 days ago | 1

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Rearranging a 512x64 matrix into a 32x1024 matrix
% Assuming A is your input matrix of size 512 x 64 % such as % A=reshape(1:512*64,64,512)'; B = reshape(permute(reshape(A,[...

14 days ago | 1

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generate random number with total sum is 10
For the case of more generic sum of n variables Xi is equal to 1. If the apriori distribution is supposed to be uniform density...

14 days ago | 1

Is fmincon appropriate for optimizing vector-valued optimization variables (scalar obj. function)?
Yes fmincon supposes to handle optimization problems on objective function that depends on vector of real values. There is no re...

15 days ago | 0

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How do I map array values on a logical array
Result = zeros(size(B)); Result(B==1)=A

15 days ago | 1

Find the line where 2 planes intersect
% Planes implicit equations are: % a1*x + b1*y + c1*z = d1; % a2*x + b2*y + c2*z = d2; % a1 = 256; b1=0; c1=0; d1=0; ...

15 days ago | 1

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subsref works as not expected
I knew it for sometime: subsref never work to emulate comma list (not sure if it's documented), because a non trivial comma list...

15 days ago | 0

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There is https://www.mathworks.com/help/optim/ug/coneprog.html but only for linear objective function. You migh iterate on b...

15 days ago | 0

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