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Christine Tobler


MathWorks

178 2015 年以降の合計貢献数

Professional Interests: numerical linear algebra, graph algorithms

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Christine Tobler's バッジ

  • 24 Month Streak
  • Revival Level 2
  • Knowledgeable Level 3
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How can I solve a sparse linear system efficiently in MATLAB?
Do you need the whole matrix A*inv(B)*A', or do you just need to apply this matrix to a vector (A*inv(B)*A'*x)? In the second ca...

10日 前 | 0

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Backslash (\) operator became much slower when updating from 2015b to 2019a
Thank you for these logs. The difference in behavior comes from the following message, saying that we repeat the factorization w...

約1ヶ月 前 | 1

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Backslash (\) operator became much slower when updating from 2015b to 2019a
Based on the spy plot, I would be astonished if a different method was selected between the two releases - I think the LU solver...

約1ヶ月 前 | 1

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Backslash error ''Warning: Matrix is singular to working precision."
For more details about what backslash does for sparse matrices, use spparms('spumoni', 1) cnew = Amat \ rhs; This will displa...

2ヶ月 前 | 1

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SVD freezes in 2018a
This sounds like a bug. It shouldn't be due to memory issues, SVD uses the same amount of memory if the matrix size and the synt...

2ヶ月 前 | 0

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generalized eigen-problom, complex non-symmetric matrix, how to find orthogonal eigenvectors
There's an easier way to compute both U and W: [U, D, W] = eig(A, B); This will make sure that the eigenvectors U(:, i) and V(...

2ヶ月 前 | 1

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Optimizing a matrix with cplexlp?
You can solve this using intlinprog. This is probably not the most efficient way of solving the problem, but reliable A = [0 1 ...

3ヶ月 前 | 1

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How SVD works for dimensionality reduction?
There's the svd function. The link points to the doc which has examples of how to use it.

3ヶ月 前 | 0

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chol fails on Hermitian positive definite matrix?
That is astonishing. The matrix is not badly conditioned, I would expect CHOL to work fine here. I tried on my machine and didn...

3ヶ月 前 | 0

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Sparsest solution for A\B
That statement is wrong, x = A\b doesn't return the solution x with the smallest number of nonzero elements. What mldivide does,...

3ヶ月 前 | 2

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eigs function: incorrect eigenvalues
The problem is that the matrix A is badly conditioned: >> cond(full(A)) ans = 2.206837183464466e+16 This is just around...

3ヶ月 前 | 2

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Plotting eigenmodes in 3D
Depending on the format of your 3D-frame, maybe you could use pdeplot3d.

4ヶ月 前 | 0

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matchpairs function in r2019a
The algorithm solves the same problem as the Hungarian algorithm, but it's not the same algorithm. The Hungarian algorithm has c...

4ヶ月 前 | 0

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Hungarian algorithm realizated in matlab
As of R2019a, there is a function matchpairs in core MATLAB (no toolboxes needed) that solves the same problem as the Hungarian ...

4ヶ月 前 | 0

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Hungary algorithm
As of R2019a, there is a function matchpairs in core MATLAB (no toolboxes needed) that solves the same problem as the Hungarian ...

4ヶ月 前 | 1

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Matching of eigenvalues of 2 matrices
With R2018a, there is a new function matchpairs which might be useful for this. Basically, it takes a matrix of similarities bet...

4ヶ月 前 | 0

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How to calculate n-th eigenvector using eigs() function
There's no way of doing this directly, and the indirect ways are hard to implement and not very robust. Also, this will be very...

4ヶ月 前 | 2

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Simulating a Markov chain
There is a specific class that represents a discrete-time Markov chain in the Econometrics toolbox: dtmc.

4ヶ月 前 | 0

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Delete Highlighted Node in a Graph?
You can use highlight to set that marker to 'none'. The GraphPlot object h contains all the graphical properties of the plotted ...

4ヶ月 前 | 0

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Yet another lu(A) question and pivoting
I'm afraid I can't post the algorithm used in mldivide. Note that it's a bit more general: it also works if both the rows and th...

5ヶ月 前 | 0

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Yet another lu(A) question and pivoting
Yes, MATLAB checks if L is a permuted triangular matrix. See the doc for mldivide - Algorithm for full inputs. However, it's st...

5ヶ月 前 | 1

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In sparse matrix eigs(A,k,sigma), how to specify both shift and direction
With a numeric sigma, EIGS uses a linear system solve (A-sigma*I)\v instead of A*v to compute the largest eigenvalues of the inv...

5ヶ月 前 | 0

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Is there a way to obtain all cycles of a directed graph similar to all_simple_cycles() in sage?
There's no direct function, but I've attached a solution I've quickly put together just now. This recursively iterates through a...

5ヶ月 前 | 0

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How to generate all the matrices of graphs for given numbers of vertices and edges?
I've attached a script that computes this for n=4 and e=3. This script will not scale well to larger numbers of nodes and edges,...

5ヶ月 前 | 0

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Which algorithm eig () function use ?
There are different algorithms for solving eigenvalue problems, depending on the properties of the inputs. The most well-known s...

5ヶ月 前 | 0

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Shotest path between any two nodes in the graph
To read data from Arcmap, you would probably need to use the Mapping Toolbox (for example shaperead). To use the shortest path a...

6ヶ月 前 | 0

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graph weight overlap and arrow size
There isn't a solution for this at the moment, unfortunately. One alternative would be to set the LineWidth based on the edge we...

6ヶ月 前 | 0

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Is it possible to set an alpha value for each edge in a GraphPlot?
Hi Michael, We do not provide a way to set EdgeAlpha to be different for each edge. We just didn't expect this to be very usefu...

7ヶ月 前 | 0

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eig function returning complex eigen vector values for a symmetric matrix, why?
EIG checks whether the input matrix is symmetric, in which case it chooses an algorithm that always returns real matrices. It ch...

7ヶ月 前 | 2

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Mex and digraph in C++
graph, digraph and table are MATLAB objects (meaning they are implemented as .m files). There is no C++ syntax to access such ob...

7ヶ月 前 | 0

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