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Christine Tobler


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MathWorks

208 total contributions since 2015

Professional Interests: numerical linear algebra, graph algorithms

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Answered
how to do forward neighbor discovery in un-directed graph?
If I understand correctly, you want to find all nodes that are direct neighbors of n1, then all nodes that connect to n1 through...

5 days ago | 0

Answered
Using eigs with singular matrix
The 'smallestabs' option in eigs depends on solving several linear systems with the matrix A that's being passed in. If A is sin...

14 days ago | 0

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Change the alignment and font size of edgelabels
The edge labels provided with the plot of a graph can't be modified in terms of their alignment. However, you can add standard t...

15 days ago | 0

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Answered
a question for defining Custom Deep Learning Layer
You can use the svd in a custom layer, however, if the SVD is used in the forward method of a custom layer, this will likely req...

16 days ago | 0

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Answered
Control edge alpha via edge weights to visualize a dynamic network
You can set the LineStyle to be 'none' for edges that should not be displayed: >> g = digraph([3 1 2], [2 3 1], [0 0.5 1]); >>...

22 days ago | 1

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Answered
how to create a symmetric Toeplitz matrix with bounds on eigenvalues?
You can use the MATLAB function toeplitz with one input argument (two-input returns a non-symmetric Toeplitz matrix).

23 days ago | 0

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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...

28 days ago | 1

Answered
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...

29 days ago | 2

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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...

1 month ago | 1

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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...

1 month ago | 0

Answered
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 ...

1 month ago | 0

Answered
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...

2 months ago | 1

Answered
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...

2 months ago | 0

Answered
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 months ago | 2

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Answered
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 ...

2 months ago | 1

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Answered
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 ...

2 months ago | 0

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Answered
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...

3 months ago | 0

Answered
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,...

3 months ago | 0

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Answered
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...

3 months ago | 0

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Answered
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...

3 months ago | 0

Answered
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...

3 months ago | 1

Answered
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...

3 months ago | 0

Answered
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...

3 months ago | 1

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Answered
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...

3 months ago | 1

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Answered
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...

4 months ago | 0

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Answered
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...

4 months ago | 0

Answered
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 ...

4 months ago | 0

Answered
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...

4 months ago | 0

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Answered
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...

5 months ago | 0

Answered
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 .^...

5 months ago | 1

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