Bruno Luong

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1 587 total contributions since 2009

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Random derangement
Generate sequences of random derangement

ungefär 2 timmar ago | 1 download |

Answered
Why Contour matrix M ( [M,c] = contour(__) ) contains the data points exceeding xmax/ymax?
[M,h]=contourf(f,8) Return contours of 8 levels, not single level of value 8. You might use this function to decode the output...

ungefär 9 timmar ago | 0

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What frustrates you about MATLAB? #2
Some time data comes as single, but text just rejects it >> x=single(0); >> y=single(0); >> text(x,y,'Why single is not suppo...

en dag ago | 1

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How can I get randperm to return a permutation of a vector that has no entries at their original positions?
Here is an implementation of a non-rejection method and unbiased random derangement: function p = randder(n) % p = randder(n) ...

2 dagar ago | 1

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matrix in special arrangment for cycler gemetry
>> A=[11 12 13 14 15] A = 11 12 13 14 15 >> toeplitz(A,A) ans = 11 12 13 14 15 ...

3 dagar ago | 0

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how matlab stores graphics objects?
All graphic objects are class "handle". Handles is a identify to designate the object and it's obviously 8 bytes as showed by wh...

3 dagar ago | 0

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speeding up my for loop
function y=divisors2(N) f = factor(N); [~,~,J] = unique(f); n = accumarray(J,1); y = prod(n+1); end Test >> N=27022021 ...

3 dagar ago | 1

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Check if nullspace is contained in another + finding intersection of 2 nullspaces.
First question: KA = null(A); KB = null(B); % Check span KA is included in span KB PKA = KB*(KB'*KA); % Projection KA on ...

4 dagar ago | 1

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How can I get randperm to return a permutation of a vector that has no entries at their original positions?
This will do what you ask for https://www.mathworks.com/matlabcentral/fileexchange/30189-randpermfull?s_tid=srchtitle Even bet...

4 dagar ago | 0

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Theory of Bicubic interpolation
It has been answered here https://www.mathworks.com/matlabcentral/answers/78116-algorithm-of-bicubic-interpolation In 2D you d...

7 dagar ago | 0

Submitted

Free-knot spline approximation
Least squares approximation of 1D data using free-knots spline

7 dagar ago | 23 downloads |

Answered
Finding LAT LONG inside a circle of a given LAT LONG .
% Random data lonA=rand*360; latA=rand*180-90; n = 10000; lonP=rand(1,n)*360; latP=rand(1,n)*180-90; earthradius = 6357;...

11 dagar ago | 0

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HELP. Need to understand MATH behind scatteredInterpolant or Interp2 function
"Based on the equation that I had in that screen shot would you assume that the other model is using a simplified linear interpo...

13 dagar ago | 0

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How to generate a nearly symmetric matrix?
Just generate first a symettric matrix then perturb a "the overwhelming minority" of elements. Whatever that definnition means....

14 dagar ago | 1

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HELP. Need to understand MATH behind scatteredInterpolant or Interp2 function
Run this, that show the "formula" and how to get zq = -38.5561 zq_check = -38.5561 Code to check 'linear' met...

14 dagar ago | 0

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In a vector, how to remove neighbours too close from one another
Using stock function >> uniquetol([1 6 12 17 23 25 34],10,'DataScale',1) ans = 1 12 23 34 Jan's various ...

18 dagar ago | 2

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Generate random integers that sums to a specific number within a specific range
Unfortunately the uniform distribution with bounds for integer is much more challenging. One way is to approximate by rounding t...

20 dagar ago | 0

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How to calculate the pairwise distince between two dataset without any loop
If you have latest MATLAB release (for pagemtimes) and download this Multiple same size solver FEX X = [1 2 1;3 4 2;5 6 3] Y =...

24 dagar ago | 0

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How could I separate the geometry data from single stl file contains multiple objects by stlread?
You can use conncomp of the triangulation graph data=stlread('research_stl_read.stl'); s=data.ConnectivityList(:,[1 2]); t=...

27 dagar ago | 1

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Why the abbrevation of "Left side of equation" is "lhs"
left hand side

28 dagar ago | 2

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How to Find the Rotation Matrix?
You equation is NOT enough to determine the third column, you forget about the orthogonal conditions and that det(R)=1 (rotation...

30 dagar ago | 3

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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)...

ungefär en månad ago | 2

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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...

ungefär en månad 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...

ungefär en månad 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...

ungefär en månad 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...

ungefär en månad 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...

ungefär en månad ago | 2

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

ungefär en månad ago | 0

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

ungefär en månad ago | 1

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Answered
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 ...

ungefär en månad ago | 1