Community Profile # Christine Tobler

### MathWorks

Last seen: 1 día hace Con actividad desde 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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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...

3 días 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'...

24 días hace | 0

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

27 días 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...

alrededor de 1 mes 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...

alrededor de 2 meses hace | 0

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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...

alrededor de 2 meses hace | 0

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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...

3 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 ...

3 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...

3 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 ...

3 meses hace | 0

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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 ...

4 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 ...

6 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...

6 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 ...

6 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...

6 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...

8 meses hace | 0

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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)...

8 meses 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...

8 meses hace | 0

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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 ...

9 meses hace | 0

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new interface for QR decomposition in Matlab 2022a
Yes, we made this change for R2022a. I'm sorry this has caused problems for you, @Klaus Diepold, could you share how you had bee...

10 meses hace | 1

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how to find eigenvalues using the determinant ?
The determinant should only be used explicitly to solve an eigenvalue problem for symbolic calculation (for example, when you so...

10 meses hace | 2

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GUI crashes when using eigs with a nonzero shift on a large generalised eigenvalue problem.
Ideally this shouldn't crash, but produce an out-of-memory error. However, for example on Linux there is the "out-of-memory kill...

12 meses hace | 0

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GPU speed up for pcg() is disappointing
It looks like you can simply replace your current call to pcg with x = pcg(A, b, tol, 5000, @(y) L\y, @(y)L'\y); as the error ...

alrededor de 1 año hace | 0

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What is matlab doing under the hood when I solve this generalized eigenvalue problem?
You can use the Display option to get some more information on what's going on inside of eigs. load matrices.mat [V,D] = eigs(...

alrededor de 1 año hace | 1

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Trapz error in calculating 2D integrals: ORDER contains an invalid permutation index
Replace the line I = cumtrapz(y,cumtrapz(x,MBerry(keySet),2)); with I = cumtrapz(y,cumtrapz(x,MBerry(keySet),2), 1); Here'...

alrededor de 1 año hace | 0

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`svd` sometimes blows up - how to fix it?
In short, the problem is that pinv_modified is based on a misunderstanding of the workaround here. The idea is to check if SVD f...

alrededor de 1 año hace | 1

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Calculating node coordinates for a graph without plot command
Unfortunately there isn't a way to get these coordinates without plotting. I have added your request for such a function to our ...

alrededor de 1 año hace | 1

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'MarkerEdgeColor' for Graph/Digraph Nodes
Yes, MATLAB's graph and digraph plots only have one NodeColor property which applies to both the marker's FaceColor and EdgeColo...

alrededor de 1 año hace | 0

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How to convert a graph / edges list into a shapefile (.shp) ?
There isn't a direct way to do this with a graph object. The mapping toolbox has a shapewrite function which produces a .shp fil...

alrededor de 1 año hace | 0

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Condition number of empty matrix
The case of a 0-by-0 matrix doesn't have any very useful definition, as you note correctly in the comments above. MATLAB does w...

más de 1 año hace | 1