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Christine Tobler


MathWorks

195 2015 年以降の合計貢献数

Professional Interests: numerical linear algebra, graph algorithms

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Why are eigenvector matrices computed by matlab not idempotent
Hi Marco, You seem to be confusing two terms: A matrix M is idempotent if ; it's orthogonal if , which is what you are testing ...

2日 前 | 1

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Warning: Matrix is close to singular or badly scaled. Results may be inaccurate. RCOND = 7.252760e-17.
As lambda approaches an eigenvalue of A (which is the goal of your algorithm), the matrix A - lambda*eye(size(A)) becomes close ...

4日 前 | 1

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How to compute efficiently A^(-1)*(1-exp(-A*h))?
For most sparse matrices expm(A) will be dense, so that should be expected to be expensive with a 1e4-by-1e4 matrix. If you are ...

5日 前 | 0

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How to add svd(singular value decomposition) in a custom layer
When dlarray supports a function, this means, most of all, that it supports automatic differentiation of this function - which f...

10日 前 | 0

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How to add svd(singular value decomposition) in a custom layer
Yes, this is because SVD is not supported for dlarray. For its first release in R2019b, dlarray supports about 80 basic methods,...

11日 前 | 0

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Open just some Graph Edges in Variable Editor and let the user modify them?
That's tricky: In terms of assignment, if G.Edges(i, :) is assigned to, the graph class interprets this as assigning to all elem...

22日 前 | 0

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how get graph?
Since MATLAB R2015b, there are Graph and Network Algorithms in MATLAB that will allow you to construct and plot a graph of these...

22日 前 | 0

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Connected graph given adjacency matrix
I realize this is an old question, but since it's still getting visits, I have a small addition. As of R2015b, the new graph and...

22日 前 | 1

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Extract eigenvalues and eigenvectors / Symbolic to numeric / Rayleigh-Ritz Method / Vibro-acoustics
The problem is making i and j into symbolic variables, which leads to the symbolic engine not knowing that these are real intege...

26日 前 | 0

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Graph visualization adding white to my nodes. How to solve it?
I'd assume this problem will also happen with other graphics elements. Could you try the following code and let me know if you'r...

約1ヶ月 前 | 1

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Shortest path through node group sets
There is no direct graph-based algorithm to solve this. I would suggest using the optimization toolbox to define this as an opti...

約1ヶ月 前 | 1

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Error using 'graph' function in matlab R2019b
Could you try starting a new MATLAB and just enter the following code: >> A = ones(3); >> G = graph(A); If this gives the err...

約2ヶ月 前 | 0

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how to avoid floating point error and figure out a way to break out of this loop such that it generates correct answer
There has been a lot of research on how to deal with floating-point error in the Lanczos algorithm, see the Wikipedia page for s...

約2ヶ月 前 | 0

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Why my eigenvalues from (v,d)=eig(k,m) are so close to each other?
Since you mentioned eigenvalues converging at a certain number in the context of FEA analysis: This is usually not the case for ...

約2ヶ月 前 | 0

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Does the function "ode45" use matrix decomposition?
ODE45 does not use a decomposition or solve a linear system with A. However, ODE15s and ODE23s, which are specialized for "stiff...

約2ヶ月 前 | 0

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could anyone help me to calculate the euclidean distance for the matrix.
Hi Bruno, I have the same problem where I can't comment on your answer, so adding another answer here. That's a good point - ve...

3ヶ月 前 | 0

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could anyone help me to calculate the euclidean distance for the matrix.
For MATLAB R2017b or later, you can use the vecnorm function for a simpler construction than the one involving sqrt, sum, and .^...

3ヶ月 前 | 1

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Hi just want to know if someone can maybe help me i have this matrix t want to get the eigenvector but it give me complex values and im pretty sure it must not be complex values for that matrix
A simple way to verify if the returned eigenvalues are correct is to compute both the eigenvalues and the eigenvectors, and to c...

4ヶ月 前 | 1

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How can I solve a sparse linear system efficiently in MATLAB?
Do you need the whole matrix A*inv(B)*A', or do you just need to apply this matrix to a vector (A*inv(B)*A'*x)? In the second ca...

4ヶ月 前 | 0

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Backslash (\) operator became much slower when updating from 2015b to 2019a
Thank you for these logs. The difference in behavior comes from the following message, saying that we repeat the factorization w...

5ヶ月 前 | 1

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Backslash (\) operator became much slower when updating from 2015b to 2019a
Based on the spy plot, I would be astonished if a different method was selected between the two releases - I think the LU solver...

5ヶ月 前 | 1

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Backslash error ''Warning: Matrix is singular to working precision."
For more details about what backslash does for sparse matrices, use spparms('spumoni', 1) cnew = Amat \ rhs; This will displa...

6ヶ月 前 | 1

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SVD freezes in 2018a
This sounds like a bug. It shouldn't be due to memory issues, SVD uses the same amount of memory if the matrix size and the synt...

6ヶ月 前 | 0

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generalized eigen-problom, complex non-symmetric matrix, how to find orthogonal eigenvectors
There's an easier way to compute both U and W: [U, D, W] = eig(A, B); This will make sure that the eigenvectors U(:, i) and V(...

6ヶ月 前 | 1

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Optimizing a matrix with cplexlp?
You can solve this using intlinprog. This is probably not the most efficient way of solving the problem, but reliable A = [0 1 ...

6ヶ月 前 | 1

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How SVD works for dimensionality reduction?
There's the svd function. The link points to the doc which has examples of how to use it.

7ヶ月 前 | 0

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chol fails on Hermitian positive definite matrix?
That is astonishing. The matrix is not badly conditioned, I would expect CHOL to work fine here. I tried on my machine and didn...

7ヶ月 前 | 0

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Sparsest solution for A\B
That statement is wrong, x = A\b doesn't return the solution x with the smallest number of nonzero elements. What mldivide does,...

7ヶ月 前 | 2

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eigs function: incorrect eigenvalues
The problem is that the matrix A is badly conditioned: >> cond(full(A)) ans = 2.206837183464466e+16 This is just around...

7ヶ月 前 | 2

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Plotting eigenmodes in 3D
Depending on the format of your 3D-frame, maybe you could use pdeplot3d.

7ヶ月 前 | 0

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