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...

12ヶ月 前 | 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 ...

12ヶ月 前 | 0

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...

12ヶ月 前 | 2

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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 ...

1年弱 前 | 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 ...

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 ...

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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...

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 ...

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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...

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...

1年以上 前 | 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)...

1年以上 前 | 0

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...

1年以上 前 | 1

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 ...

1年以上 前 | 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...

1年以上 前 | 1

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...

1年以上 前 | 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...

1年以上 前 | 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 ...

2年弱 前 | 0

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(...

2年弱 前 | 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'...

2年弱 前 | 0

`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...

2年弱 前 | 1

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 ...

2年弱 前 | 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...

2年弱 前 | 0

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...

2年弱 前 | 0

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...

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How to fix **Warning: Matrix is close to singular or badly scaled. Results may be inaccurate. RCOND = 1.053110e-20.** ?
Yes, the matrix A becomes singular after applying the last two for-loops (which I think are the boundary conditions). You can v...

How to check if there is an edge between two nodes in an undirected graph?
Call findedge(g, node1, node2). If there is no edge connecting these nodes, the output is zero. Otherwise, the output is the ind...

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Why does lu function yield different lower triangle matrix if I return [L,U] rather than [L, U, P]?
The LU decomposition really involves three new matrices: An upper-triangular matrix U, a lower-triangular matrix L, and a permut...

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How to find a permutation matrix to turn a general hermitian matrix into a block diagonal one?
First, we should keep in mind that the task is really to find a representation of A with as small blocks on the diagonal as poss...

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Interpreting eigenvalues and eigenvectors when using symbolic toolbox
I'm getting both 4 eigenvalues and 4 eigenvectors when running your code: linkMatrix = [0,1/3,1/3,1/3; 0,0,1,0; ...

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Different behaviour in indexing between table and digraph node table
This is a bug in digraph, thank you for reporting it! I have passed it along and it will be fixed in a future release.

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