Questions tagged [sparse-arrays]
Questions on the construction and manipulation of sparse arrays in Mathematica, with functions like SparseArray[] and Band[].
335 questions
5
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How to quickly extract a consecutive portion of a sparse vector?
Say I have this very sparse vector of gigantic size:
...
- 113k
3
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1
answer
98
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BinCounts: force/block SparseArray output
BinCounts sometimes outputs data as SparseArray, and sometimes Normal.
This does not depend ...
- 2,690
1
vote
2
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166
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Creating a large sparse array
I want to create a large sparse matrix by given 2 matrices with dimensions of $m\times m$ and $n\times n$. It will not be $6\times 6$ as in the picture, I only tried to give a simple example. I do not ...
- 105
4
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1
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292
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How does Mathematica MatrixExp Krylov method scale with sparse matrices? [closed]
People say that mathematica is not as good as matlab for nunmerics. For my specific use case, I am trying to solve differential equations with the MatrixExp method ...
- 444
1
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0
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137
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Efficient eigenvalue calculation of large matrix
My question is related to my issue from yesterday (Initializing very large matrices). It was recommended to use SparseArray to initialize large matrices efficiently....
- 53
3
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2
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198
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Best way to extend the size and add terms to a SparseArray without expanding
Let's say I have a "small" SparseArray of any size, in the example $2\times2$
...
- 37.7k
3
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1
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There is a mistake when using SparseArray in the Table function
I discovered a difference between version 12.0 and version 14.0 in how they handle SparseArray within the Table function.
For ...
- 33
0
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0
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134
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Efficient construction of Hermitian block matrix
I need to construct large Hermitian matrices $H$, which can be built out of blocks. The matrix $H$ is of total size $Lx\times Ly$, with blocks of size $Ly$. For $Lx=5,\,Ly=3$ and $L=2$ (which is the ...
- 85
3
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1
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268
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Arnoldi method for generalized eigenvalue problem with sparse matrices
I would like to solve a generalized eigenvalue problem involving sparse matrices using the Arnoldi method. I would like to use the Arnoldi method in the hope of speeding up the calculation.
Problem is,...
- 453
6
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1
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Workaround for SparseArray "ExplicitPositions" in version 12.0
I have some work that utilizes the "ExplicitPositions" property of Sparse Arrays that was at least available starting at version 13.0. However, I am trying to run some of my work on a ...
- 1,156
4
votes
2
answers
192
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Speed up sparse Hermitian matrix-vector product
I am interested in speeding up as much as possible the dot product in the specific case of a multiplication of a $n\times n$ sparse hermitian matrix $H$ (where $n$ is typically large, let's say $\...
- 315
6
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1
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198
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MapIndexed on a table of SparseArray structures produces different output in Mathematica 12 and 14.0
Here is a snippet I use to dynamically define a bunch of functions f[i][x_]:
...
- 525
7
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3
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291
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Counting non-zero multiplications in large sparse matrix multiplications
Suppose I have several large, fixed, sparse matrices of real-valued entries. To make things simple, assume each is $n \times n$. I will multiply them, e.g., matA.matB.matC. Of course I can reduce ...
- 43.3k
3
votes
2
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262
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Creating a sparse matrix
I would like to create the following sparse matrix
\begin{equation}
A =
\begin{pmatrix}
a1+b1 t & k-1 & 0 & \ldots &0 \\
a2^{2}+b2^{2} t & a1+b1t & k-2 & \ldots &0 \...
- 1,085
5
votes
2
answers
307
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Efficiently construct a SparseArray of a given "shape"
I have a given SparseArray, let's call it A.
I want to construct another SparseArray, let's call it B, which has the same "shape" as A.
Right now, I construct B by applying a certain ...
- 453