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Christine Tobler

MathWorks

Last seen: 1 giorno fa Attivo dal 2015

Spoken Languages:
English, French, German
Pronouns:
She/her
Professional Interests:
Graph and Network Algorithms, Linear Algebra, Quantum Computing, Automatic Differentiation

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Risposto
getting warning while using eigs on the matrices obtained from freefem++
If modifying the input sigma doesn't help, it's likely that for your call eigs(A, B, sigma, ...) the matrices are such that A - ...

11 giorni fa | 0

| accettato

Risposto
Trying to construct a filtered graph using pmfg function that uses the (MATLAB-BGL) library in MacBook.
The problem seems to be with the MatlabBGL FileExchange package and specifically with the .mex files that are being provided the...

11 giorni fa | 0

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Risposto
Can I get all of the shortest paths between all pairs of nodes in a Directed Graph in one function call
Using shortestpathtree in a loop over the starting node is the way to go. You can change the data format of the first output by ...

circa un mese fa | 1

Risposto
Inconsistency between Matlab eig() function and Matlab generated C code eig() function
For code generation, the eig function doesn't have as many special-case treatments as the eig function in regular MATLAB. This m...

circa un mese fa | 2

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Risposto
How to control the curvature of each edge when drawing graph object?
The curvature of the edges in this plot aren't controllable. You could turn off the edges from the graph plot, and use the plot ...

circa 2 mesi fa | 1

Risposto
eigs function works slowly
A possible issue is that "largestreal" option works less towards the strengths of the EIGS algorithm than the default "largestab...

circa 2 mesi fa | 0

Risposto
Why is my parfor loop running slower than a regular for loop
The problem is likely that the cost of each iteration is still too small to warrant the start-up time of the parfor loop. You c...

2 mesi fa | 0

Risposto
Quick method in solving symmetric linear equation
You can definitely use iterative methods such as pcg. The success of this usually depends on how well-conditioned your matrix is...

4 mesi fa | 1

Risposto
doc QR decomposition error
Hi, As you can see here, R is an m by n matrix and Q is an m by m matrix in the default behavior of the qr function: A = randn...

4 mesi fa | 0

Risposto
Replacing old version graphshortestpath with new shortestpath function
You can replace [ dist,path{1} ] = graphshortestpath( adjMatrix, 1, numel(newImg(:))); with [ path{1}, dist ] = shortestpath(...

5 mesi fa | 0

Risposto
Eigenvalues and Eigenvector computation on extremely bad conditioned matrices
If the matrix P has rank 120 and its size is 160, you should expect 40 eigenvalues to be Inf - this is how singularities in the ...

5 mesi fa | 0

Risposto
QR factorization of a low rank matrix
Let's start with computing a rank-2 approximation of a large matrix. In general, this would be done using the SVD, but if you kn...

5 mesi fa | 0

Risposto
Can additional information be added to the directed graph plotting node 'tooltip'?
Yes, you can do this using the dataTipTextRow function: nodeNames = {'Node A', 'Node B', 'Node C', 'Node D', 'Node E', 'Node F'...

6 mesi fa | 0

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Risposto
computational complexity of svds
There is a recent function (introduced R2020b) called svdsketch, which is using randomized linear algebra. We recommend this for...

6 mesi fa | 0

Risposto
Write Hamiltonian using kron function
For a 6-dimensional Kronecker product, you would want to take Sz = [1 0; 0 -1]; I = [1 0; 0 1]; and apply the Kronecker produ...

6 mesi fa | 0

Risposto
Algorithm for edge connectivity of a digraph?
There is no direct method in MATLAB for computing the edge connectivity. Based on the Wikipedia page, you should be able to comp...

7 mesi fa | 0

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Risposto
Get coordinates of 3-D force-directed graph plot without plotting?
There isn't currently such a function available. For the example above, nearly all the time is being spent in computing the coo...

7 mesi fa | 0

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Risposto
Obtain eigs from matrix and partially known eigenvector
Hi Jennifer, You are right that matrix P here is a block-diagonal matrix with three blocks: [A 0 0; 0 B 0 0 0 C] And for su...

8 mesi fa | 1

| accettato

Risposto
finding degree and neighbor of each vertex in a subgraph H but indexing according to original graph
I think the easiest will be to build on what you started by giving the nodes in graph G names which are just the string version ...

8 mesi fa | 0

Risposto
Change of parameters of Gates in quantumCircuit does not take effect
This is a bug, thank you for reporting it. As a workaround while waiting for this to be addressed, pleaseconstruct a new gate in...

8 mesi fa | 1

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Risposto
how to find neighbors/degree of hyperedges of a uniform hypergraph?
MATLAB doesn't support hypergraphs, but often a specific problem can be solved with just a graph or multigraph, by interpreting ...

8 mesi fa | 0

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Risposto
LU decomposition algorithm change
As you point out, this kind of difference in result is to be expected and is well withing expected round-off behavior. Another ...

9 mesi fa | 1

Risposto
How can I plot a multilayer graph (2 layer) starting from adjacency matrices?
Here's an example of how to do this (using just some random data, since I don't have the matrices you mention above). % Choose ...

11 mesi fa | 1

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Risposto
How to create a random graph that is connected?
If an undirected graph is connected, it must contain at least one path that visits each node at least once. You could construct...

11 mesi fa | 0

Risposto
I have a question about the distributed computing of the eig function.
EIG for distributed arrays calls into the ScaLAPACK library - the references given by ScaLAPACK documentation would be the best ...

11 mesi fa | 1

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Risposto
non linear eigen value problem
This isn't the standard definition of a nonlinear eigenvalue problem, where you would have only one scalar lambda. Am I underst...

11 mesi fa | 0

Risposto
Issues with the normalisation of mode shapes?
eig(A, B) normalizes the eigenvectors in the B-mass norm, but only if it recognizes the input as a symmetric problem (A is symme...

circa un anno fa | 0

| accettato

Risposto
Proof of relation between the generalized singular values of gsvd(A,B) and gsvd(B,A)
The background for this is the 5-output form of the GSVD: [U,V,X,C,S] = gsvd(A,B) returns unitary matrices U and V, a (usually)...

circa un anno fa | 0

Risposto
Update a sparse matrix efficiently
The fastest way to construct a sparse matrix will be when the inputs are sorted, first by columns and then by rows. You can veri...

circa un anno fa | 1

Risposto
Given a big square matrix and some eigenvalues, how to find the corresponding eigenvectors?
I wouldn't expect a 3072-by-3072 matrix to be a problem on the machine you describe. Could you try to run the following on your ...

circa un anno fa | 0

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