Questions tagged [sparse-arrays]
Questions on the construction and manipulation of sparse arrays in Mathematica, with functions like SparseArray[] and Band[].
300
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Insert a dynamic vector into a matrix
If I have the following dynamic vector
Cs[NN_] :=
Table[{Sin[(2*i - 1) τ], Sin[(2*i - 1) τ]}, {i, 1, NN}] //
Flatten
The size of Cs depends on the integer ...
- 1,163
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1
answer
69
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0
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0
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34
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Trying to map SparseArray over a defined list, the SparseArray defined with 3 subvalues i want to map the 3rd. subValue(list) over the defined list
I have a SparseArray already defined as following
...
- 1
1
vote
0
answers
50
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Erratic behavior retrieving large data (several tens of gigabytes) that has been serialized by Mathematica
Hardware: PC with 256GB RAM
OS: Windows 10
Mathematica: Version 13.0.1
One of my projects has led to the creation of a SparseArray whose ByteCount is ~ 35GB in RAM. At the time of creation the ...
- 2,024
2
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1
answer
80
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Define a function with sparsearray
I am trying to define a function using SparseArray, but the entries were defined before. How can I avoid this error?
Code is:
...
- 111
1
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0
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Why does Sparsearray diagonalization by Krylov technique become slower for very large sizes?
Here is an example sparse matrix, taken from example Hamiltonian, which was a question I asked before in this forum.
...
- 479
2
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0
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22
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Threshold on triangular SparseArray
I am confused by the behavior of Threshold on sparse UpperTringularize (and LowerTringularize...
- 7,503
3
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0
answers
68
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Fastest Way to make rows and columns zero and corresponding (i,i) element 1 of a large Sparse Matrix
I have a 5552 by 5552 sparse matrix:
...
4
votes
3
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230
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Generating signed permutation matrices
As most people (on here at least) know a permutation matrix is a square binary matrix that has exactly one entry of 1 in each row and each column and 0s elsewhere. For the $n \times n$ case there are $...
- 485
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100
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Defining a SparseArray functions in Mathematica 13
I am defining a sparse array as a function of argument x, i.e.
f[x_] = SparseArray[{1->x}, {3}]
In Mathematica 12 this works perfectly, I can pass arguments and ...
- 71
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0
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62
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How to convert an SparseArray into a Matrix?
I have the following sparse array and I want to change it to a matrix. Could you please tell me how to do that?
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2
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1
answer
56
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How to create a 3D matrix from different blocks?
I would like to generate a $3D$ matrix of dimension $(n1\times n1\times n1)$ compose of $216$ matrix blocks $(n2\times n2\times n2)$. All 216 matrix blocks are subdivided into 4 groups, each one with ...
- 1,100
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SparseArray Input
How to create a SparseArray without using lists of rule in MMA?
In MMA we can define a SparseArray using lists of rule
...
- 1,624
7
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0
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51
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Is there a way to make SparseArray distinguish between background values of different precision that are numerically equal?
To illustrate what I mean, consider the following:
SparseArray[{{1} -> 1, {5} -> 1.}, Automatic, 0] // Normal
{1, 0, 0, 0, 1.}
As you can see, the ...
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25
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2
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0
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96
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Building a Matrix as a piecewise-function of the indices without for loops [closed]
I'm very new to Mathematica and this site. I've read that building matrices with For loops is slow, and I have experienced this myself on the current project. I'm trying to wrap my head around ...
- 21
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0
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72
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How to efficiently build a large sparse matrix and overloading a compiled function?
I would like to construct a large sparse matrix folding from rank-4 tensor given by the following:
$\mathcal{L}_{1L}^{00}(i,j)=\mathcal{L}_{1L}^{00}(m_1,m_2;M_1,M_2)$
The indices of matrix $(i,j)$ are ...
- 425
6
votes
2
answers
252
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Speedup the production of a sparse symmetric matrix with a dense vector
The optimization of the production of a sparse symmetric matrix with a dense vector has existed for a long time. Someone once compared the matrix operations of Mathematica with MATLAB, and then came ...
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2
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83
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1
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1
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Why does generating a list of elements for SparseArray crash the kernel?
I am trying to create a sparse matrix by the SparseArray command. For a set of index pairs $(i,j)$ I want to calculate the $A_{i,j}$ element and then use this ...
- 243
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0
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29
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Implementing array with partial cyclic data?
I'd like to construct an array where some columns are cyclic. As an illustrative example, take
Table[Mod[k, 2^i], {k, 2^10}, {i, 0, 10}] //Grid,
where the vast ...
- 611
2
votes
1
answer
223
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Diagonal matrix command in Mathematica
How to find the corresponding Mathematica commands for diagonal matrix operation in Matlab, e.g.
AA=rand(3,3);
Step 1.) finding the diagonal elements, and export ...
- 1,624
3
votes
1
answer
96
views
How to write correctly some arguments in SparseArray
I am struggling to put an argument in SparseArray. Let's consider the following example
...
- 45
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0
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60
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Parallelizing construction of sparsearray
I'm constructing sparse arrays where blocks of each array are results of the integral defined in integralList
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1
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2
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115
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Improving large array manipulation
I am doing an iterative program, which uses large arrays/vectors and where the output of one round is used as an input for the next steps but works slowly when dimensions are bigger.
In brief, we ...
- 45
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0
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47
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sparse matrix multiplication
Say I have a sparse matrix $M$ with $\sim 50.000 .000$ non zero elements.
What is the fastest way to make operations such as :
$$M^k X$$
where $X$ is a given vector.
Is the operation $MX$ ...
- 912
1
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1
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45
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Fastest way to convert two associations into a sparse matrix
I have two association $N$ and $C$
$N$ has this form :
$N=<|x_1\rightarrow \{x_{1,1},...x_{1,p_1}\},x_2\rightarrow \{x_{2,1},...x_{2,p_2}\}...,x_D\rightarrow \{x_{D1},...x_{Dp_D}\} |>$
$C$ has ...
- 912
9
votes
1
answer
172
views
Efficiently populate a Sparsearray for a set of rules for a constrained basis
I want to populate quite a large SparseArray(10^6 x10^6) efficiently. It is basically a spin system Hamiltonian with a constrained Hilbert space. Unlike the examples I have looked at in this forum ...
- 479
1
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0
answers
80
views
1
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1
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81
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Lowest Eigenvalue of a large sparse matrix without choking up the RAM (Corrected) [closed]
I am trying to find the lowest eigenvalue of a large sparse matrix of dimension N (=$3^n$, where n is number of particles in system ) using ...
- 902
3
votes
1
answer
114
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Memory leak when creating a SparseArray
Problem: I have a list e={u,v,w} and wish to construct a sparse matrix with entries {u[i],v[i]}->w[i]. Note that the same ...
- 1,095
2
votes
0
answers
99
views
What is the fastest way to get the lowest eigenvalue and corresponding eigenstate in Mathematica?
I tried to use the Arnoldi method to get the smallest eigenvalue and corresponding eigenstate for large matrix. However, Arnoldi did not give me the desired result:
...
- 657
6
votes
1
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142
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Efficient construction of a SparseArray from LIL (list of lists of column entries)
In Python scipy.sparse, there are methods to convert between CSR, CSC, LIL, DOK, etc. implementations of a sparse matrix. What is the most efficient way in Mathematica to construct a ...
- 1,095
4
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0
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122
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Insufficient memory problem in Mathematica
I am trying to initialize a 48600 x 48600 packed array from a sparse matrix and a diagonal matrix in Mathematica 8. If S1 is a sparsearray of that size then and S2 is list of 48600 length, then I am ...
- 479
4
votes
2
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119
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How to efficiently upsample a greyscale image to generate a representative binary image
I want to create binary images by upsampling a series of greyscale images (192 x 144 resolution) by a factor of 10 with the new pixel values being a pseudorandom distribution of 0's & 1's based on ...
- 3,623
3
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2
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143
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Creating a block matrix from arrays of blocks
I am trying to generate a matrix from square blocks. Effectively, I have a $n×n$ matrix polynomial $P(l)$, the $qth$ derivative of $P(l)$ with respect to $l$, which is denoted by $P^{(q)} (l)$, and a ...
- 41
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2
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201
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Permute association key and generate a sparse array
Imagine having an Association
Av = <|{1, 4, 2, 3} -> a, {2, 4, 2, 4} -> b|>
It can be much longer. I am searching ...
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1
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65
views
How can I define a function using ArrayFlatten without using SetDelayed?
I created a matrix F2 using SparseArray and ArrayFlatten as follows:
...
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0
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61
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Seeming inconsistencies with "Eigenfunction" [duplicate]
I am working on a problem which involves calculating the spectrum of a family of 2970x2970 Hermitian matrices. I have done similar things with Mathematica in the past, but this time there is an odd, ...
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1
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Construct a matrix from blocks of matrices [closed]
I am trying to find eigen values of a matrix system where entries of the matrix are also matrix. This is how my matrix looks:
$$ M=\begin{bmatrix}
H[j,j] & T[j,j+1] & 0 &0 &....
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2
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Elegant way to construct a matrix with symbolic entries
I would like to construct a matrix $G$ composed of block matrices $G^{(i)}$ as defined entry-wise below stacked vertically as
$$G = \begin{bmatrix} G^{(1)} \\ G^{(2)} \\ \vdots \\ G^{(i)} \\ \vdots \\ ...
- 179
3
votes
1
answer
57
views
How do I pass indices to a function when constructing a SparseArray?
I am trying to speed up my Mathematica code, so instead of testing and calculating the same thing again and again I want to save the result in a SparseArray. The goal is to generate a matrix which I ...
- 1,005
0
votes
1
answer
108
views
Import and export a list of SparseArrays efficiently?
I have a list of integers dims and a list of SparseArrays bdrs (representing a chain complex ...
- 1,095
0
votes
0
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53
views
How to find the rank of a sparse-array list without memory leaks?
I have a very wide list of sparse arrays (I basically just used the numbers as an encoding mechanism for vectors of polynomials), and I want to find out whether they're linearly independent. How ...
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7
votes
1
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242
views
Efficiently populate sparse matrix with band structure
I'm trying to efficiently populate elements of a very large (2^20 x 2^20) symmetric matrix with 1s - luckily the matrix is very sparse, <0.1% filling. Further, the matrix has a very well defined ...
- 811
9
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3
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272
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Multiplying two complex SparseArray objects, yielding empty SparseArray crashes kernel
Problem:
When I multiply together two sparse matrices that should give back the 0 matrix, where at least one element among the two is complex and at least one is not an exact number, the kernel ...
- 1,814
8
votes
1
answer
268
views
SparseArray to list of lists (column entries) efficiently?
Suppose we have a very big very sparse matrix, e.g.:
...
- 1,095
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0
answers
57
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How to apply PolynomialMod to a SparseArray?
I have a list bdrs of SparseArrays, whose entries are polynomials in the variable t with ...
- 1,095
10
votes
2
answers
239
views
`Count` for `SparseArray`
Why does Count not work with SparseArrays, and is there any function I can use to replace it?
What would be an efficient ...
- 459
7
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0
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127
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Memory usage for smallest eigenvalues
I have a bunch of hermitian matrices which are huge (of order 2^17 x 2^17) but extremely sparse so that, when I build the matrices, the usage of RAM is low (say of order 1 GB or similar).
The ...
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