Answered

missing eigenvector when using eig on defective matrix

The short answer is that this is a case where a small change in the input matrix has a large effect on the eigenvectors being co...

missing eigenvector when using eig on defective matrix

The short answer is that this is a case where a small change in the input matrix has a large effect on the eigenvectors being co...

10 maanden ago | 1

| accepted

Answered

THE GRAPH FUNCTION DOESN'T CONSIDER WEIGHTS

Hard to say what's going wrong without seeing your code. Here's an example where you can see the weights being used to decide on...

THE GRAPH FUNCTION DOESN'T CONSIDER WEIGHTS

Hard to say what's going wrong without seeing your code. Here's an example where you can see the weights being used to decide on...

10 maanden ago | 1

| accepted

Answered

mldivide (backslash): advantage by using sparse matrix instead of a full matrix with respect to the quality of the results?

The condition estimate used in mldivide to decide if a warning should be given is much less accurate for the sparse case. This i...

mldivide (backslash): advantage by using sparse matrix instead of a full matrix with respect to the quality of the results?

The condition estimate used in mldivide to decide if a warning should be given is much less accurate for the sparse case. This i...

11 maanden ago | 2

| accepted

Answered

LDL does not support complex symmetric matrices

Largely the reason LDL doesn't support this is that it's less commonly requested for complex symmetric matrices than for complex...

LDL does not support complex symmetric matrices

Largely the reason LDL doesn't support this is that it's less commonly requested for complex symmetric matrices than for complex...

11 maanden ago | 0

| accepted

Answered

Inconsistency in behavior of SVD

Firstly, I agree completely with John's great explanations above: Any singular value below eps*first singular value should be tr...

Inconsistency in behavior of SVD

Firstly, I agree completely with John's great explanations above: Any singular value below eps*first singular value should be tr...

11 maanden ago | 3

| accepted

Answered

Accuracy Problem when solving linear equation system using: lu(S) vs. decomposition(S,'lu')

The version in decomposition does some optional steps of iterative refinement: It uses the same solution you have above based on...

Accuracy Problem when solving linear equation system using: lu(S) vs. decomposition(S,'lu')

The version in decomposition does some optional steps of iterative refinement: It uses the same solution you have above based on...

11 maanden ago | 0

| accepted

Answered

Need help fixing errors on code written in old MATLAB syntax

I'd also recommend replacing the calls svd(A) and svd(A, 0) with calling svd(A, 'econ'), since the code here is only using the f...

Need help fixing errors on code written in old MATLAB syntax

I'd also recommend replacing the calls svd(A) and svd(A, 0) with calling svd(A, 'econ'), since the code here is only using the f...

12 maanden ago | 0

Answered

Different results on different computers, Matlab 2021b - 64 bit, windows 64 bit, both Intel chips

First, about "which value to trust?" Both values are equally trustworthy, the differences in results come down to applying the ...

Different results on different computers, Matlab 2021b - 64 bit, windows 64 bit, both Intel chips

First, about "which value to trust?" Both values are equally trustworthy, the differences in results come down to applying the ...

12 maanden ago | 1

| accepted

Answered

eigs with Extended Capabilities

The first of these would only be useful if you need to apply EIGS to many problems in parallel, in which case each of these coul...

eigs with Extended Capabilities

The first of these would only be useful if you need to apply EIGS to many problems in parallel, in which case each of these coul...

12 maanden ago | 1

Answered

How to parallelize many small SVD's on a GPU

As of R2021b, there is a function pagesvd which is supported on both CPU and distributed arrays. It's not supported for gpuArray...

How to parallelize many small SVD's on a GPU

As of R2021b, there is a function pagesvd which is supported on both CPU and distributed arrays. It's not supported for gpuArray...

12 maanden ago | 2

| accepted

Answered

How does shortestpath function work?

Every edge has a number, which is the order in which they appear in the Edges table (try displaying g.Edges). The edgepath conta...

How does shortestpath function work?

Every edge has a number, which is the order in which they appear in the Edges table (try displaying g.Edges). The edgepath conta...

12 maanden ago | 1

| accepted

Answered

Eigs passes the wrong StartVector

The standard method used in EIGS is only efficient for matrices that are quite large. When eigs detects that the input matrix is...

Eigs passes the wrong StartVector

The standard method used in EIGS is only efficient for matrices that are quite large. When eigs detects that the input matrix is...

12 maanden ago | 0

| accepted

Answered

How to enhance the performance of Matalb's function sqrtm?

Not in general. You might be able to find a cheaper but less accurate way to compute this, but if that's acceptable would depend...

How to enhance the performance of Matalb's function sqrtm?

Not in general. You might be able to find a cheaper but less accurate way to compute this, but if that's acceptable would depend...

ongeveer een jaar ago | 0

Answered

fastest path between more than two nodes

To compute simply the shortest-path distance, you can use the distances function and pass in a graph object you've constructed u...

fastest path between more than two nodes

To compute simply the shortest-path distance, you can use the distances function and pass in a graph object you've constructed u...

ongeveer een jaar ago | 1

Answered

Follow a complex eigenvalue in a spectrum at different times

You could try using the matchpairs function: rng default; d = randn(20, 1) + 1i*randn(20, 1); d2 = d + 0.1*(randn(20, 1) + 1i...

Follow a complex eigenvalue in a spectrum at different times

You could try using the matchpairs function: rng default; d = randn(20, 1) + 1i*randn(20, 1); d2 = d + 0.1*(randn(20, 1) + 1i...

ongeveer een jaar ago | 0

| accepted

Answered

Error using eig in Matlab 2021b by using Parallels 17 of Macbook Pro (M1 )

Since MATLAB is trying to load a .dll file, I'm assuming you're running a Windows VM on this Macbook Pro. MATLAB doesn't support...

Error using eig in Matlab 2021b by using Parallels 17 of Macbook Pro (M1 )

Since MATLAB is trying to load a .dll file, I'm assuming you're running a Windows VM on this Macbook Pro. MATLAB doesn't support...

ongeveer een jaar ago | 0

| accepted

Answered

use of svds with function handles

The svds function needs to be able to apply both A*x and A'*x, so your function handle should accept a second input which is eit...

use of svds with function handles

The svds function needs to be able to apply both A*x and A'*x, so your function handle should accept a second input which is eit...

ongeveer een jaar ago | 2

Answered

How to compute cholesky to all slice of a tensor?

There isn't another way to do this right now. We have functions that do other linear algebra operations to each page of an ND-ar...

How to compute cholesky to all slice of a tensor?

There isn't another way to do this right now. We have functions that do other linear algebra operations to each page of an ND-ar...

ongeveer een jaar ago | 1

Answered

Why does mldivide solve equations so fast that FORTRAN can't compare it？

MATLAB's mldivide uses multithreading. It doesn't use the GPU unless you have the Parallel Computing Toolbox and are using the g...

Why does mldivide solve equations so fast that FORTRAN can't compare it？

MATLAB's mldivide uses multithreading. It doesn't use the GPU unless you have the Parallel Computing Toolbox and are using the g...

ongeveer een jaar ago | 0

Answered

How to highlight single edges in an undirected graph?

Do you still want the multiple edges to be displayed? If not, you can use the simplify command to reduce all multiple edges to j...

How to highlight single edges in an undirected graph?

Do you still want the multiple edges to be displayed? If not, you can use the simplify command to reduce all multiple edges to j...

ongeveer een jaar ago | 1

| accepted

Answered

Unable to find out left eigen vectors of symbolic matrix

The left eigenvectors are still expressed as right eigenvectors of M', meaning they satisfy a slightly different equation: syms...

Unable to find out left eigen vectors of symbolic matrix

The left eigenvectors are still expressed as right eigenvectors of M', meaning they satisfy a slightly different equation: syms...

ongeveer een jaar ago | 0

| accepted

Answered

Program to find connected and non-isomorphic graphs

In the last loop, you are checking if adj is isomorphic to any previous graph. If there is one graph that adj is not isomorphic ...

Program to find connected and non-isomorphic graphs

In the last loop, you are checking if adj is isomorphic to any previous graph. If there is one graph that adj is not isomorphic ...

ongeveer een jaar ago | 0

| accepted

Answered

How can I invert a big matrix e.g. 1000-by-1000

When running inv on this matrix, there's a warning: >> M = inv(current_Fit_Mat); Warning: Matrix is close to singular or badly...

How can I invert a big matrix e.g. 1000-by-1000

When running inv on this matrix, there's a warning: >> M = inv(current_Fit_Mat); Warning: Matrix is close to singular or badly...

meer dan een jaar ago | 0

Answered

Add an automatic TOC to an .mlx

You can go the "Insert" tab (just to the right of where it says "Live Editor" on top of the MATLAB window) and there's a button ...

Add an automatic TOC to an .mlx

You can go the "Insert" tab (just to the right of where it says "Live Editor" on top of the MATLAB window) and there's a button ...

meer dan een jaar ago | 0

Answered

How to get a Table Contents in Live Script .mlx export to HTLM

You can go the "Insert" tab (just to the right of where it says "Live Editor" on top of the MATLAB window) and there's a button ...

How to get a Table Contents in Live Script .mlx export to HTLM

You can go the "Insert" tab (just to the right of where it says "Live Editor" on top of the MATLAB window) and there's a button ...

meer dan een jaar ago | 0

Answered

How is SVDS execution time related to the target rank?

So the goal of svds is usually to compute a requested rank that is much smaller than either size of the input matrix. A search s...

How is SVDS execution time related to the target rank?

So the goal of svds is usually to compute a requested rank that is much smaller than either size of the input matrix. A search s...

meer dan een jaar ago | 0

| accepted

Answered

How to solve eigs/checkInputs issue in EOF analysis?

The error here is happening because R eof>mycaleof is an empty matrix, and eof is trying to compute an eigenvalue of it. Looking...

How to solve eigs/checkInputs issue in EOF analysis?

The error here is happening because R eof>mycaleof is an empty matrix, and eof is trying to compute an eigenvalue of it. Looking...

meer dan een jaar ago | 0

Answered

How to make the color in the "highlight" function stronger and well defined (not pale/transparent as by default) ?

Set h.EdgeAlpha = 1;

How to make the color in the "highlight" function stronger and well defined (not pale/transparent as by default) ?

Set h.EdgeAlpha = 1;

meer dan een jaar ago | 0

| accepted

Answered

How to find out isolated subgraph?

The component output in your code is the number of components. You can use the second output of conncomp to get a vector contai...

How to find out isolated subgraph?

The component output in your code is the number of components. You can use the second output of conncomp to get a vector contai...

meer dan een jaar ago | 1

Answered

Find all cycles (or the initial node of each cycle) in a very large directed graph (12m nodes, 6.7m edges)

Have you tried using 'MaxNumCycles' to only compute the first 100 / 1000 / 1e4 cycles? That could give some indication if it's c...

Find all cycles (or the initial node of each cycle) in a very large directed graph (12m nodes, 6.7m edges)

Have you tried using 'MaxNumCycles' to only compute the first 100 / 1000 / 1e4 cycles? That could give some indication if it's c...

meer dan een jaar ago | 1

| accepted