Professional Interests: numerical linear algebra, graph algorithms

Answered

Shortest path through nodes

As Bjorn mentioned, this is the traveling salesman problem. The optimization toolbox has an example of how to use their intlinpr...

Shortest path through nodes

As Bjorn mentioned, this is the traveling salesman problem. The optimization toolbox has an example of how to use their intlinpr...

15 días ago | 1

| accepted

Answered

lsqminnorm- Tolerance to Reduce Impact of Noisy Data

The tolerance in lsqminnorm should be used if you expect your matrix A to be of low rank up to a tolerance. That is, for rank k,...

lsqminnorm- Tolerance to Reduce Impact of Noisy Data

The tolerance in lsqminnorm should be used if you expect your matrix A to be of low rank up to a tolerance. That is, for rank k,...

15 días ago | 0

Answered

How do I get Matlab to display a graph type data structure with decreasing weights

The Edges table attached to a digraph is always standardized so that its sorted by the EndNodes column. However, you can get a c...

How do I get Matlab to display a graph type data structure with decreasing weights

The Edges table attached to a digraph is always standardized so that its sorted by the EndNodes column. However, you can get a c...

15 días ago | 0

| accepted

Answered

Ordering edge names in Digraph

The edges are reordered in the graph constructor, but it looks like the Power variable you're assigning is in the same order as ...

Ordering edge names in Digraph

The edges are reordered in the graph constructor, but it looks like the Power variable you're assigning is in the same order as ...

17 días ago | 0

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Answered

SVD of each row of a matrix

The SVD of a row vector has the singular value equal to its norm, and the singular vectors 1 and the normalized vector. If this...

SVD of each row of a matrix

The SVD of a row vector has the singular value equal to its norm, and the singular vectors 1 and the normalized vector. If this...

24 días ago | 0

| accepted

Answered

qr decomposition run-time performance

When a "~" is used for a return value, this is only for code clarity. MATLAB still needs to compute that value, so the second ca...

qr decomposition run-time performance

When a "~" is used for a return value, this is only for code clarity. MATLAB still needs to compute that value, so the second ca...

24 días ago | 2

Answered

Sign difference between coeff=pca(X) and [~,~,v] = svd(X)

I'm not sure why this happens. As mentioned by others, it doesn't matter what sign these outputs have. You could try stepping th...

Sign difference between coeff=pca(X) and [~,~,v] = svd(X)

I'm not sure why this happens. As mentioned by others, it doesn't matter what sign these outputs have. You could try stepping th...

24 días ago | 1

Answered

How to use non-unique node names in a digraph?

Instead of setting these inputs as node names, add them as a separate variable in the nodes table. Then, pass them to the plotti...

How to use non-unique node names in a digraph?

Instead of setting these inputs as node names, add them as a separate variable in the nodes table. Then, pass them to the plotti...

alrededor de 2 meses ago | 0

| accepted

Answered

Is there any way to accelerate the solving of a series of large sparse positive definite linear equations "Ax=b" with same "A" and different "b"?

If you are able to solve for one vector using A \ b, you could pass in a matrix containing all your right-hand sides in instead:...

Is there any way to accelerate the solving of a series of large sparse positive definite linear equations "Ax=b" with same "A" and different "b"?

If you are able to solve for one vector using A \ b, you could pass in a matrix containing all your right-hand sides in instead:...

alrededor de 2 meses ago | 2

Answered

Accelerate eigs with GPU

The eigs function is not supported on the GPU. There is support for sparse matrices on the GPU, since R2015a: Release notes para...

Accelerate eigs with GPU

The eigs function is not supported on the GPU. There is support for sparse matrices on the GPU, since R2015a: Release notes para...

alrededor de 2 meses ago | 1

Answered

Properties of adjacency matrix

In terms of the adjacency matrix, a disconnected graph means that you can permute the rows and columns of this matrix in a way w...

Properties of adjacency matrix

In terms of the adjacency matrix, a disconnected graph means that you can permute the rows and columns of this matrix in a way w...

alrededor de 2 meses ago | 0

Answered

Assigning values to an array of arbitrary dimensions in MATLAB.

Using the somewhat recent implicit expansion, this can also be done without indexing into every element of the array: function ...

Assigning values to an array of arbitrary dimensions in MATLAB.

Using the somewhat recent implicit expansion, this can also be done without indexing into every element of the array: function ...

2 meses ago | 0

Answered

How to find all edges indexes if node indexes are given?

So you're looking for all edges where both end nodes are part of the set 4, 5, 6? This will compute them: >> [s, t] = findedge(...

How to find all edges indexes if node indexes are given?

So you're looking for all edges where both end nodes are part of the set 4, 5, 6? This will compute them: >> [s, t] = findedge(...

2 meses ago | 0

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Answered

Create random graph with limited degree

You could start by just making an undirected graph, and then go through each node and compute its degree. If the degree is large...

Create random graph with limited degree

You could start by just making an undirected graph, and then go through each node and compute its degree. If the degree is large...

2 meses ago | 0

Solved

Maximum of ND-array

Find the maximum element of a N dimensional array. Example: A=[1 2 4 ; -20 4 10]; The maximum is 10.

2 meses ago

Answered

Result of A(:,:,1,1) coming as result of A(:,:,1,2)

The eigenvectors returned by EIG are returned in the same order as the eigenvalues, but the eigenvalues are not necessarily sort...

Result of A(:,:,1,1) coming as result of A(:,:,1,2)

The eigenvectors returned by EIG are returned in the same order as the eigenvalues, but the eigenvalues are not necessarily sort...

3 meses ago | 0

Answered

How to find all related nodes in directed graph?

Another option is to use the weak connected components of the graph: bins = conncomp(G, 'Type', 'weak'); % bins(nid) gives th...

How to find all related nodes in directed graph?

Another option is to use the weak connected components of the graph: bins = conncomp(G, 'Type', 'weak'); % bins(nid) gives th...

3 meses ago | 0

Answered

rotation of graph node labels

The labels will be straight in most layouts (all but 'circle', 'layered'). You can first use 'circle' layout and then convert to...

rotation of graph node labels

The labels will be straight in most layouts (all but 'circle', 'layered'). You can first use 'circle' layout and then convert to...

3 meses ago | 0

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Answered

Error using matlab.graphics.chart.primitive.GraphPlot/highlight>checkSubgraph

Try using Gsol = graph(idxs(ledge,1),idxs(ledge,2), [], numnodes(G)); so that G and Gsol both have the same number of nodes. T...

Error using matlab.graphics.chart.primitive.GraphPlot/highlight>checkSubgraph

Try using Gsol = graph(idxs(ledge,1),idxs(ledge,2), [], numnodes(G)); so that G and Gsol both have the same number of nodes. T...

3 meses ago | 0

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Answered

About "eigs" function

This was the case for old EIGS, it would use some random restart vectors that changed on every run. In the version of EIGS that ...

About "eigs" function

This was the case for old EIGS, it would use some random restart vectors that changed on every run. In the version of EIGS that ...

3 meses ago | 1

Answered

Assign Numerical Node Labels

For the first call, use >> GG.Nodes.Name = num2str(Name)' - GG.Nodes.Name has to be a column vector. For the second call,...

Assign Numerical Node Labels

For the first call, use >> GG.Nodes.Name = num2str(Name)' - GG.Nodes.Name has to be a column vector. For the second call,...

3 meses ago | 0

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Answered

How to find inverse of a 608*608 matrix fast?

The matrices in this file are symbolic, it's very expensive to compute with large arrays of these variables. If you cast it to f...

How to find inverse of a 608*608 matrix fast?

The matrices in this file are symbolic, it's very expensive to compute with large arrays of these variables. If you cast it to f...

3 meses ago | 0

| accepted

Answered

Is it possible to recover *the* decomposition that's ultimately employed by mldivide (backslash)?

The same decomposition is used, the difference is in the estimation of the condition number. MA57 provides an estimate of the co...

Is it possible to recover *the* decomposition that's ultimately employed by mldivide (backslash)?

The same decomposition is used, the difference is in the estimation of the condition number. MA57 provides an estimate of the co...

3 meses ago | 3

Answered

"eig" use which algorithm to find eigenvalues

We don't give out the exact method used, but all syntaxes of EIG call into various LAPACK functions. See here for an introductio...

"eig" use which algorithm to find eigenvalues

We don't give out the exact method used, but all syntaxes of EIG call into various LAPACK functions. See here for an introductio...

3 meses ago | 0

Answered

sortrows graph edges .

The variable G.Edges.EndNodes of a graph can't be modified, it is always sorted by the nodes in the graph. This is so that the p...

sortrows graph edges .

The variable G.Edges.EndNodes of a graph can't be modified, it is always sorted by the nodes in the graph. This is so that the p...

3 meses ago | 1

Answered

How to find all the downstream nodes from a node in a graph?

You can call nearest(G, 1, Inf) which will find all nodes reachable from node 1 in an infinite radius. This will contain only...

How to find all the downstream nodes from a node in a graph?

You can call nearest(G, 1, Inf) which will find all nodes reachable from node 1 in an infinite radius. This will contain only...

4 meses ago | 1

Answered

Find border edges of the graph

The graph class doesn't have any functions based on coordinates of the points - it just knows about their connections. Use conve...

Find border edges of the graph

The graph class doesn't have any functions based on coordinates of the points - it just knows about their connections. Use conve...

5 meses ago | 1

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Answered

QR decomposition with the output of a permutation vector

The purpose of arranging all diagonal elements in descending order is to allow splitting R into two parts if A is low-rank or cl...

QR decomposition with the output of a permutation vector

The purpose of arranging all diagonal elements in descending order is to allow splitting R into two parts if A is low-rank or cl...

5 meses ago | 0

| accepted

Answered

How to add highlighted nodes and edges of a graph to the legend?

The problem here is that legend will only provide labels for what graphics recognizes as individual objects. So in a line plot,...

How to add highlighted nodes and edges of a graph to the legend?

The problem here is that legend will only provide labels for what graphics recognizes as individual objects. So in a line plot,...

5 meses ago | 1

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Answered

How to restore tensor after applied the PARAFAC model?

The three component vectors represent the 3 different dimensions here. For the one-component case (all are vectors), you can use...

How to restore tensor after applied the PARAFAC model?

The three component vectors represent the 3 different dimensions here. For the one-component case (all are vectors), you can use...

5 meses ago | 0

| accepted