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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...

mehr als 5 Jahre vor | 0

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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...

mehr als 5 Jahre vor | 3

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"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...

mehr als 5 Jahre vor | 0

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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...

mehr als 5 Jahre vor | 2

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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...

mehr als 5 Jahre vor | 1

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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...

fast 6 Jahre vor | 1

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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...

fast 6 Jahre vor | 0

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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,...

fast 6 Jahre vor | 1

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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...

fast 6 Jahre vor | 0

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Create a graph from removed edges
The graph constructor has a syntax that specifies the number of nodes of the graph: graph(s, t, [], numnodes) if you pass the ...

fast 6 Jahre vor | 0

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SVD computation using eig function
Try the formula the other way around, using U_tilde, V_tilde and A to compute D: >> U_tilde'*A*V_tilde ans = 70.0118 -0....

fast 6 Jahre vor | 0

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Using Singular value decomposition for feature extraction from images
Image compression using SVD is a pretty common example (although not the most efficient way to compress an image), here are some...

fast 6 Jahre vor | 0

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Error using eig Input matrix contains NaN or Inf.
The function sossolve is part of a third-party tool, this seems to be their website: http://www.cds.caltech.edu/sostools/. It's ...

fast 6 Jahre vor | 0

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How to keep track of order eigenvalue in eig or eigs?
The eigenvalues returned by EIG are not sorted in any particular order generally (for some special types of matrices (e.g. exact...

fast 6 Jahre vor | 2

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Eigenvectors and the null function
I'm getting those two eigenvectors when I copy your code into MATLAB: >> D = [2 -1; -1 3]; eigs = eig(D); q1 = nu...

fast 6 Jahre vor | 0

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Block-diagonalization of a matrix
There is no direct function to do this. The best is probably to write a function that does a loop through the different blocks a...

fast 6 Jahre vor | 0

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How created a graph from unordered node list?
When a graph or digraph is specified using numbers, the assumption is that all nodes of this graph have numbers from 1:numberOfN...

fast 6 Jahre vor | 0

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nonsingular matrix (X) in GSVD function
These are just different but equivalent definitions: Both will result in the same C and S, the only difference is in how X is re...

fast 6 Jahre vor | 1

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accuracy of two methods to solve eignvalues/eignvector problem
The second way is typically more accurate, because it doesn't incur additional round-off error when conputing inv(Sw) and when m...

fast 6 Jahre vor | 0

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Sort eigenvectors matrix.
Take a look at rsf2csf. For a block-diagonal matrix with 1-by-1 and 2-by-2 blocks, it computes a diagonal eigenvalue matrix and ...

fast 6 Jahre vor | 1

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Eigenvectors of an SPD matrix being saved as complex doubles
EIG does not recognize the input matrix as symmetric because it's not exactly symmetric. If you compute A = Y'*Mh*Y norm(A - A...

fast 6 Jahre vor | 0

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Given a matrix A^n. Comparing normal multiplication versus Diagonalization. I expect the former to be faster but its not in my case
A^2 is just one matrix multiplication, A*A, which is much faster to do directly than the call to EIG. For larger n, A^n isn't ...

fast 6 Jahre vor | 0

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how to random initialize svd function in matlab??
The linear algebra functions in MATLAB are run-to-run reproducible, meaning if you call them twice with the exact same input, yo...

fast 6 Jahre vor | 1

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EigenValues of a Vibrating system
Usually for finite element problems, the stiffness matrix is passed in as the first input, and the mass matrix as the second inp...

fast 6 Jahre vor | 0

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issues with Cholesky decomposition
This can happen if your matrix is close to symmetric positive semi-definite (meaning the smallest eigenvalue is around machine e...

fast 6 Jahre vor | 0

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Can I preserve adding order when calling graph/addedge?
The edges in a graph are always presented in the same order (sort first by source node, secondarily be target node). You can mai...

fast 6 Jahre vor | 1

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Display only one eigenvalue of symbolic matrix
The eigs function is not supported for symbolic values, as it is specifically based on getting a good approximation based on an ...

fast 6 Jahre vor | 0

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how to do forward neighbor discovery in un-directed graph?
If I understand correctly, you want to find all nodes that are direct neighbors of n1, then all nodes that connect to n1 through...

etwa 6 Jahre vor | 1

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Using eigs with singular matrix
The 'smallestabs' option in eigs depends on solving several linear systems with the matrix A that's being passed in. If A is sin...

etwa 6 Jahre vor | 0

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Change the alignment and font size of edgelabels
The edge labels provided with the plot of a graph can't be modified in terms of their alignment. However, you can add standard t...

etwa 6 Jahre vor | 0

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