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# Christine Tobler

### MathWorks

202 total contributions since 2015

Professional Interests: numerical linear algebra, graph algorithms

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Interpolation for n-dimensional array data
I don't think interpn would work very well for you: The U, S and V matrices returned by SVD are not linearly dependent on the in...

1 dag ago | 1

eigs gives wrong eigenvalues
Edit: Please see the comment below, the first answer I gave here was going in the wrong direction. Thank you for the detailed d...

3 dagen ago | 1

How can I solve linear equation system in parallel?
As John says, if you are using decomposition on one computer with several cores, the solver used already will use those cores if...

9 dagen ago | 1

Why Power of Matrix with decimal values gives really big numbers?
For a Markov Chain, you need the sum of each row to be 1 (as this represents the probability to transition to any state), and ev...

11 dagen ago | 0

Which Right Eigenvector to report?
The left and right eigenvectors are matched one-by-one. For example, for [V, D, W] = eig(A), the eigenvalue D(k, k) corresponds ...

17 dagen ago | 0

eigs for generalized eigenvalue problem ( [V,D] = eigs(A,B) ) with spars matrix
A bug was introduced in R2017b in eigs for matrices with exact zero eigenvalues. This bug has been fixed in R2019a, the fix appl...

ongeveer een maand ago | 1

Error using eig Input matrix contains NaN or Inf from images
The variable covariance_matrix contains non-finite values (either Inf meaning infinity, returned for example from 1/0, or NaN me...

ongeveer een maand ago | 0

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 ...

ongeveer een maand ago | 2

| accepted

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 ...

ongeveer een maand ago | 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 ...

ongeveer 2 maanden ago | 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...

ongeveer 2 maanden ago | 0

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,...

ongeveer 2 maanden ago | 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...

2 maanden ago | 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...

2 maanden ago | 0

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...

2 maanden ago | 1

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...

2 maanden ago | 0

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...

2 maanden ago | 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...

2 maanden ago | 1

| accepted

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...

3 maanden ago | 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...

3 maanden ago | 0

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 ...

3 maanden ago | 0

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...

3 maanden ago | 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...

4 maanden ago | 0

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 .^...

4 maanden ago | 1

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...

5 maanden ago | 1

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...

5 maanden ago | 0

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...

6 maanden ago | 1

| accepted

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...

6 maanden ago | 1

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...

7 maanden ago | 1