Questions on the construction and manipulation of sparse arrays in Mathematica, with functions like SparseArray[] and Band[].

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-2
votes
1answer
72 views

Recreating in Mathematica a matrix created in Python [closed]

I need to recreate in Mathematica this matrix that I created in Python: ...
1
vote
2answers
92 views

Filing matrix by bands [closed]

I need to fill a matrix, CSI, by taking elements from an array, inverse, which is the Inverse Fast Fourier Transform of an array ...
2
votes
1answer
54 views

sparse array with list [closed]

i'm trying to populate a sparse array with lists in certain positions, i tried the following code, ...
2
votes
1answer
81 views

speeding up creation of SparseArray

I have to create the following sparse arrays, which are reshaped in a two dimensional matrix, so that i can use the build in Dot[] function to do a kind of ...
1
vote
2answers
100 views

Checker rut for over 7 digit numbers

In Chile the RUT identifier identity, every rut has a check digit module 11 is used, I made this code to 7 digits, but not me 8 digits, a number of 7 digits is the abcdef- form (check digit ) and ...
5
votes
4answers
503 views

Elegant mehod of generating this matrix?

Good evening, I need to determine an elegant (as possible) method of computing an nxn matrix below (the matrix shown is just a 16x16 example). I've been toying with For loops, Tables, Bands, ...
4
votes
0answers
29 views

Bug? Kernel Crash on SparseArray access [duplicate]

Bug introduced in 7.0 or earlier and persisting through 10.0.2 or later The following simple code ...
4
votes
1answer
53 views

SparseArray output triggers “unsafe dynamic content” warning

The first basic example in the documentation of SparseArray: ...
7
votes
1answer
135 views

Instant kernel crash when using `+=` on `SparseArray` with repeated entries

Bug introduced in 5.2 and fixed in 10.1.0 Not sure if this is known behavior or not, but the following two lines produce an instant kernel crash (I'm using Mathematica 10.0.1 Windows 64-bit): ...
1
vote
1answer
69 views

Entering block matrices, general case doesn't work

I want to enter several matrices at different positions in blocks. There is already a very similar answer here: http://mathematica.stackexchange.com/a/3562/6138 I thought that simply generalizing ...
0
votes
0answers
33 views

Permute indices of a large sparse array

I'm starting with a very large rank 3 tensor, F, that is stored as a SparseArray, and I need to permute its indices. I first tried using ArrayRules to get the positions of the non-zero elements, to ...
2
votes
2answers
55 views

editing entries of a sparse array + sparse Smith normal form

Why does the following code ...
10
votes
2answers
210 views

Temporal database reconstruction in mathematica

<EDIT> after some internet research I found the database domain that deals with this kind of thing: Temporal Databases. I think my question therefore becomes how to reconstruct a temporal ...
12
votes
1answer
262 views

How to use SparseArray in CUDA?

Sparse arrays are widely used in many scientific applications where memory and time are strictly limited. For a considerable speedup one can use CUDA. Since Mathematica 8 we can conveniently use CUDA ...
3
votes
1answer
243 views
13
votes
1answer
188 views

Why won't SparseArray let me store values with the head List?

When you attempt to define a SparseArray with elements that have the head List it complains: ...
4
votes
1answer
157 views

Efficient Dyson series implementation

I'm trying to implement a Dyson series \begin{array}{lcl} U(x,x_0) & = & 1 + \int_{x_0}^{x}{dy_1V(y_1)}+\int_{x_0}^x{dy_1\int_{x_0}^{y_1}{dy_2V(y_1)V(y_2)}}+\cdots \\ & &{} + ...
4
votes
1answer
93 views

Parallelizing sparse array construction

I have a very large sparse array, and the computation of individual matrix elements is fairly expensive. The Matrix is Hermitian and traceless, so I would like to construct only the sub-diagonal ...
3
votes
1answer
128 views

How can I efficiently ArrayFlatten a matrix of sparse matrices?

I have a matrix of sparse matrices that I want to convert to a sparse block matrix. So, basically I want what ArrayFlatten does, except that I want the output to be ...
1
vote
1answer
67 views

Conditions in SparseArray

I got confused by {i_, j_} /; in the following code. I didn't see an explanation in the SparseArray documentation. Can anyone ...
0
votes
1answer
35 views

Interactively Manipulate SparseArrays or Lists

I'd love to use SparseArrayor List to group a set of parameters together in a function. ...
7
votes
1answer
120 views

Possible bug: SparseArray Part assignment loses default value?

fixed in 10.0.2 This sure looks like a bug to me (Mathematica 10.0.0, MacOS): ...
7
votes
1answer
162 views

Building sparse array from packed arrays

Suppose I have two large packed arrays a and b, that respectively contain the position of the elements of a square matrix (i.e. ...
1
vote
1answer
65 views

Devising a sparse array rule

Suppose I have a matrix A={{1, 2}, {3, 4}} that defines the positions of non-zero values in a sparse array: ...
2
votes
2answers
227 views

Create a matrix of matrices using Band and ArrayFlatten [duplicate]

I can easily write a simple Band matrix using: SparseArray[{Band[{2, 1}] -> a}, {Dim, Dim}] where a is a number. Now, I ...
0
votes
1answer
51 views

What's wrong with my rule? [duplicate]

Consider a simple code to form a SparseArray: Q = 5; a = Table[i, {i, Q}]; SparseArray[{{j_} /; j > 2 -> a[[j]]}, {Q}] Part::pspec: Part specification j ...
3
votes
1answer
345 views

Transforming a huge rectangular table to Sparse Array

I am interested in the most efficient way to transform a huge rectangular array to a sparse array structure. Consider a numeric rectangular table that is rather sparse, with zero positions being set ...
3
votes
1answer
205 views

Are there any more time-efficient ways to solve a matrix equation than with SparseArray and LinearSolve?

I am trying to solve a matrix equation, with the matrix being tridiagonal. The problem I am having is that a message keeps appearing that I don't have enough memory. Here is the code: ...
2
votes
1answer
154 views

How to handle a sparse array of lists

I have data in the form of a sparse array of lists. For example: ...
5
votes
0answers
103 views

SparseArray internal structure [duplicate]

According to the documentation: SparseArray is treated as a raw object by functions like AtomQ and for purposes of pattern ...
12
votes
2answers
207 views

Bug with SparseArray selector in Pick

I have created a notebook with two cells. This is the content of the first: ...
4
votes
2answers
126 views

Values (or positions) of array row elements within a specified number of positions from target value

I have the need to collect values from the rows of rectangular arrays of arbitrary precision integers, given a target element value and allowed "distance" (positions +/- within the row from found ...
1
vote
2answers
187 views

Manipulating sparse array elements

Suppose I have two sparse arrays ...
11
votes
3answers
736 views

Find the eigenvector associated with the smallest eigenvalue, not smallest in magnitude

I am trying to find the eigenvector of a $20000 \times 20000$ sparse matrix associated with the smallest eigenvalue. I realized that the smallest eigenvalue might be negative; for example, if the ...
4
votes
3answers
505 views

Finding elements from a sparse matrix

I am dealing sparse matrices of very large dimensions. I need to locate the positive and negative elements of the matrices and make lists of their corresponding positions. Of course I can write a ...
0
votes
0answers
68 views

Is there a faster way to do Normal[SparseArray[{{1,1,1}→1.2, {1,1,2}→20.2, …, {m,n,p}→0.3}]]?

I have a list of the form {{1,1,1}→1.2, {1,1,2}→20.2, ..., {m,n,p}→0.3} and I want to create an $m \times n \times p$ array, $A$, where the value of $A[[i,j,k]]$ is ...
0
votes
0answers
46 views

Addition of sparse array objects [duplicate]

I have been having some trouble with the addition of large (but very sparse) matrices using SparseArray. Here is the simplest example to illustrate the issue. First, I will define diagonal matrices ...
10
votes
1answer
188 views

Sporadic bugs in multidimensional SparseArray objects

Udate This SparseArray[] bug is (apparently) fixed on version 10.0 ...
2
votes
1answer
129 views

Product of non-zero elements in sparse array

How can I multiply the non-zero elements of a SparseArray? Example: ...
1
vote
1answer
116 views

Specify positions in a SparseArray using patterns with functions

I spent some time trying to figure out what was what was making so slow the calculation of the following array(actually this is only a SUPERsimple toy model): Input to the array: ...
3
votes
0answers
81 views

Efficient storage of Kronecker sum of circulant matrices+diagonal matrix

I have a square matrix of the form $$M=D+\overset{N}{\underset{n=1}\bigoplus}R_n,$$ where $R_n$ are circulant matrices, $D$ is a diagonal matrix and $\oplus$ is Kronecker sum. Its size is quite big, ...
3
votes
1answer
113 views

Opposite function to Normal

Is there any function opposite to Normal? For example, let as say that I have an SparseMatrix A, then, let as say that for convenience for a certain operation like Packing, I convert it into an Array ...
4
votes
2answers
205 views

Upsampling matrix by inserting zeros inbetween elements

I want to essentially take an image with $n \times n$ pixels and expand it into a sparse array, spacing out the pixels by a factor $2$ or $3$. Each pixel in the input image occupies one of the corners ...
6
votes
2answers
184 views

Additive SparseArray Assembly

The goal is to assemble a SparseArray in an additive fashion. Let us assume we have a large List of indices (some will be ...
1
vote
3answers
105 views

ArrayRules for a ragged list

Let there be a sample list as , l = {a, {{b, c}}, {d, e}, {f}, {{g, {y}, u, h}, {{{{k, j}}}}},k, {{{{q}, {w}, {r}, {x}}}}}; ArrayRules[l] ArrayRules::rect: ...
2
votes
1answer
198 views

How to create a SparseArray satisfying multiple conditions on Parts and Elements of a Matrix?

I have a matrix m1 of size $3 \times 19$. Rows $1$, $2$ and $3$ represent $3$ different groups, and columns represent $4$ different blocks: block1 - columns $1$, ...
4
votes
3answers
349 views

SparseArray row operations

Given a large (very) sparse matrix, A, how can I efficiently "operate" on only the nonzeros in a given row? For example: For each row in A, generate a list of column indices that have a magnitude ...
2
votes
0answers
81 views

Det and MatrixRank freezes on SparseArray with nonzero default value

Why does the following simple code never come to an end (at least with version 8) n = 5; mat = SparseArray[{i_, i_} -> 1, {n, n}, -1/(n - 1)]; MatrixRank[mat] ...
4
votes
1answer
132 views

Assigning Sequence to Part of a SparseArray (bug?)

Part ▪ You can make an assignment like t[[spec]]=value to modify any part or sequence of parts in an expression. ▪ If ...
0
votes
1answer
218 views

Is it in general faster to get the eigenvectors and eigenvalues of a dense array rather than a sparse array?

I always thought that things in general go faster when working with sparse array but, I got this: Eigenvalues::arhm: Because finding 144 out of the 144 ...