Community Profile # Christine Tobler

### MathWorks

Last seen: 13 dagen ago Active since 2015

Professional Interests: numerical linear algebra, graph algorithms

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Finding number of independent pathways in a graph
I'd expect the call to rmedge is the most expensive here. You could instead add edge weights for every edge in the graph, and th...

14 dagen ago | 0

Feature for eigs involving just positive eigenvalues
There's no option to do so directly, since it's not a common request and there's already a lot of option names in EIGS to dig th...

27 dagen ago | 0

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Large sparse matrix LU decomposition
If the call to lu runs out of memory, but the call to decomposition(__, 'lu') doesn't, likely the reason is that decomposition u...

29 dagen ago | 0

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Facing a unbalanced matrix, such as 3*5000, why someone reduce the computational cost by svd(A*A') .
The computational complexity of svd (when using the 'econ' option, which is very necessary for matrices that are far from square...

ongeveer een maand ago | 1

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Boundary 'edges' around node(s)
There is no option to do this as part of the graph plot directly. You can achieve it by turning off the node markers (set 'Marke...

ongeveer een maand ago | 1

Minimum Spanning Tree - Path or Start-End
In general, you can't rely on the fact that a minimum spanning tree will just be one path. However, if you have a graph for whic...

ongeveer een maand ago | 0

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how to determine efficiency centrality of a node in Matlab
There isn't an efficiency centrality implemented in MATLAB. Based on the paper I quickly read, it seems you would best compute t...

ongeveer een maand ago | 0

Take a look at pdist in the Statistics and Machine Learning toolbox. If you apply this to your matrix, and then call squareform ...

ongeveer 2 maanden ago | 0

Matrix inverse with svd
Use one of A = [ 2 4 6; 8 5 7 ; 0 3 1] [U,S,V] = svd(A); V*inv(S)*U' V*(S\U') % The formula you're using above puts the par...

ongeveer 2 maanden ago | 0

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Degree and influence of line of a node in network
The only reference for DIL I could find is a 2016 paper: Evaluating the importance of nodes in complex networks, J Liu, Q Xiong...

ongeveer 2 maanden ago | 2

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How to find all the edges connecting a specific node with other nodes?
Use outedges to find the IDs of all outgoing edges, or neighbors to find all nodes connected to by these edges.

2 maanden ago | 0

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Symbolic SVD for square matrix
The computation of the SVD in symbolic mathematics involves the solving of a polynomial equation of degree given by the size of ...

2 maanden ago | 1

Betweenness Centrality, Edge betweenness
For betweenness centrality, see centrality method of graph and digraph classes. Edge betweenness is not provided.

3 maanden ago | 0

How to create random graph?
You can use s = randi(n, e, 1); t = randi(n, e, 1); G = graph(s, t, [], n); which will give you a graph with n nodes and e e...

3 maanden ago | 1

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Why do logical operators do not work with the eigenvalues of this matrix?
There's a small round-off error on the eigenvalue 1: >> TM = [0.1,0.2,0.7; 0.5,0.2,0.3;0.1,0.1,0.8]; [V,D] = eig(TM', 'vector'...

3 maanden ago | 0

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Digraph with a single constrained axis
All algorithms for graph visualization that I'm aware of will compute both x and y (and sometimes z) coordinates for the nodes. ...

3 maanden ago | 0

how would i change an undirected network into a directed network on matlab?
It depends on what you want to the directed graph to look like. To replace every undirected edge with two directed edges going i...

4 maanden ago | 1

Both eig() and eigs() function calculate different eigenvalues depending on optional input values
The problems seen here are due to M being symmetric positive semi-definite. Such a matrix is numerically singular, which can hav...

4 maanden ago | 5

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Warning: Matrix is singular to working precision: What exactly generates this warning?
The warning is generated based on an estimate of the condition number (specifically, the reciprocal condition number in 1-norm, ...

4 maanden ago | 0

Traverse a directed graph visiting all edges at least once?
There aren't any functions for MATLAB's graph object that solve this problem. Possibly you can formulate this as an optimization...

4 maanden ago | 1

How to search all elements in two cell arrays?
All right, let's assume you have a graph containing both G and H stored as graph object GH, and that this graph contains the bla...

5 maanden ago | 0

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My Hessenberg Decomposition code is not working
Your code looks correct, try it with A = randn(10) for example - this matches the outputs of HESS quite closely. When the input ...

5 maanden ago | 1

Direct Solver
The direct sparse solver (\) unfortunately doesn't have methods for complex symmetric or hermitian problems, only for real symme...

5 maanden ago | 1

Solve large linear equations with backslash operator. Why is sparse matrix solved slower than the full matrix?
Sparse linear system solvers are usually fast for sparse matrices with specific structure of where the nonzeros are placed. For ...

5 maanden ago | 0

EIGS: Why is 'smallestabs' faster than 'largestabs'?
Whether 'largestabs' or 'smallestabs' depends on the problem: 'smallestabs' needs to factorize the first input, which can make i...

5 maanden ago | 0

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What is the algorithm used by svd function?
We don't give information on what SVD algorithm we use, look up the LAPACK library for detailed descriptions. For practical pur...

5 maanden ago | 1

Inverse of higher order matrix
Another way of looking at the equations x*Q = 0 and x e = 1 is as an equation system x * [Q e] = [0 1], which you could solve us...

6 maanden ago | 0

How to decompose a 4th order tensor
The value of K1111 is overwritten with the next value in every loop iteration - is this your intention, or did you maybe mean to...

6 maanden ago | 0