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Christine Tobler

MathWorks

Last seen: 1 día hace Con actividad desde 2015

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

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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 días hace | 0

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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 días hace | 0

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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 ...

alrededor de 1 mes hace | 1

Respondida
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...

alrededor de 1 mes hace | 2

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Respondida
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 ...

alrededor de 2 meses hace | 1

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

alrededor de 2 meses hace | 0

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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 meses hace | 0

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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 meses hace | 1

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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 meses hace | 0

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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 meses hace | 0

Respondida
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 meses hace | 0

Respondida
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 meses hace | 0

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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 meses hace | 0

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

6 meses hace | 0

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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 meses hace | 0

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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 meses hace | 0

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Respondida
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 meses hace | 0

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Respondida
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 meses hace | 1

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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 meses hace | 0

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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 meses hace | 1

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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 meses hace | 0

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Respondida
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 meses hace | 1

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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 meses hace | 1

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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 meses hace | 0

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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 meses hace | 1

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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 meses hace | 0

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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...

alrededor de 1 año hace | 0

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Respondida
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)...

alrededor de 1 año hace | 0

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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...

alrededor de 1 año hace | 1

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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 ...

alrededor de 1 año hace | 0

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