Tagged Questions

Questions on the manipulation of matrices in Mathematica.

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1
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2answers
41 views

Find the indexes of dependent columns

I have a fairly large singular square matrix, of size 37 and rank 35. Is there a way to get a vector with the (groups of) indexes of the columns in the original matrix that are linearly dependent? ...
0
votes
0answers
22 views

Can anyone help me deduce a matrix inequality? [on hold]

The following lemma is taken from references firstly. Lemma 1 [1-2] Given matrices $Q=Q^{T} , F, M$ and $N$ of appropriate dimensions, then $$Q+MFN+N^{T}F^{T}M^{T}<0$$ for all $F$ satisfying ...
1
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2answers
61 views

How to extract matrix which produces given symbolic linear combinations?

Suppose I have a column matrix $\alpha$, consisting of some symbols ...
0
votes
1answer
33 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 ...
1
vote
1answer
70 views

What does it mean: “Assuming a matrix | Use a list of lists instead”?

I have entered a matrix by Insert->Table/Matrix->New. After adding it to code, Mathematica wrote a remark: "Assuming a matrix | Use a list of lists instead". ...
0
votes
0answers
36 views

How to define the block matrix and calculate it's inverse

How to define the following block matrix $$ A=\begin{bmatrix} H-G_1 & -G_1 & \ldots & -G_1 \\ -G_2 & H-G_2 & \ldots & -G_2 \\ \vdots & \ldots & \vdots & \vdots ...
1
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2answers
44 views

How to add a part of a list to a function?

I want to be able to add a specific portion of a list to a part of a function but this fucntion intakes 6 variables where as the list is of example: ...
1
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0answers
39 views

Understanding polyharmonic splines

Raul Narain and J.M. gives implementation of the thin plate polyharmonic splines in this post. Raul Narian's method is clear. J.M.'s is convenient to reuse. But J.M. used too many ...
0
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0answers
24 views

Calculate number of probabilities [migrated]

I want to calculate a number of probabilities of a+b+c=1 For a vary from 0 to 1 with an incrementing of 0.1 For ...
0
votes
1answer
47 views

LinearSolve in Mathematica, used to find square matrix

Another issue I have with Mathematica today is that I want to solve the following matrix equation: X.b=c where b and c are two vectors, and X is a square ...
1
vote
1answer
37 views

How to indroduce a value for the functions inside a matrix? [closed]

I would like to assign certain values to the X and Y variables which are inside the functions in the matrix. Thus, I would like to get a matrix with values based on the transformation in Psi matrix. ...
2
votes
1answer
165 views

Log of a Matrix

I have used the command MatrixLog[m] But it gives natural log of the matrix. How can I find the Log (to the base 2) of a matrix?
2
votes
1answer
43 views

Sort a vector of vectors of vectors

Let's hope I'm calling it well, I have this vector, or matrix, now I really don't know what it is ...
1
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0answers
47 views

Displaying a matrix as an array of solid rectangular blocks [duplicate]

I would like to plot an array of numbers as a surface, with each number the height of a square, and with the squares connected to adjacent squares with vertical rectangles, up or down as appropriate. ...
-2
votes
1answer
29 views
1
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1answer
32 views

Easy way to perform multiplication of two 2x2 matrices, that contain list elements?

I have two 2x2 matrices, which elements are lists (so overall structure can be complicated). I need to perform matrix multiplication of these 2x2 matrices as if the elements didn't have its inner ...
2
votes
1answer
98 views

matrix multiplication speed

Consider the codes below: ...
0
votes
2answers
38 views

Suggest how to do this matrix multiplication [duplicate]

Have a look at the Mathematica calculation ...
1
vote
1answer
45 views

Insert a linebreak and character repeatedly into a matrix output which is in fortranForm

Suppose I have a very long string which is a11 element of matrix a11=2*gopsv-2*Bgopsvw+2*acgmops*v+2*cgmopsv*B-2*acgmopsvB+3*gmopsvB-3*BgmopsvwB+m*w2*B +5*acgm2 +opsvB -ac*m2*w2*B +cgm2*opsvB* - ...
1
vote
0answers
23 views

How to show Output of matrix in FortranForm with “&” character?

I have a matrix. and i have shown the output of matrix one by one element in FortranForm. the problem is i want to put "&" continuation charater in output because when i am copying the data into ...
0
votes
0answers
28 views

hOW TO PUT '&' OPERATOR in output of matrix elements that are in FortranForm?

i have matrix and i have shown the output in fortranForm. but due to large characters in elements of matrix, when i copied the data into fortran Code, it does not take copied data because of line ...
0
votes
2answers
65 views

How to show output of a matrix in m(1,1)=a11 m(1,2)=a12 …in this way…i have 50 *50 size matrix

How to show output of a matrix in m(1,1)=a11 m(1,2)=a12 ...in this way......i have 50 *50 size matrix so i want to do it efficiently. output to be shown like m(1,1)=a11 (in fortranForm) m(1,2)=a12 ...
0
votes
2answers
47 views

Output of matrix in FortranForm

matr2 = Table[FortranForm[matr[[i, j]]], {i, 4}, {j, 6}] but i want output to be more like this matrix(1,1)=a11 output in ...
0
votes
0answers
108 views

Matrix multiplication

I want to multiply 1000by1000 matrices but MMA runs out of RAM. ...
0
votes
1answer
48 views

Restricting Numbers in a Matrix

I am generating a random N x N matrix, but with a certain restriction. What I'm trying to do is that when there's a "1" in a position, all neighboring positions must turn to "0" (so if [i,j] = 1, then ...
0
votes
1answer
58 views

How large can be the dimension of a complex matrix which Mathematica can handle to find its eigenalues?

I have been working with 12 cross 12 complex matrix in Mathematica , I need to work with bigger size matrix of the dimension of the order of hundreds , I was wondering if Mathematica can handle ...
0
votes
0answers
93 views

using elements from a matrix into a function

Hi this is what i have done so far i have a surface with the length "l" and width "w". and i have split this surface into m*n sub surfaces. as shown below. ...
0
votes
1answer
87 views

Integrating elements from matrix

oI'm kinda new at using Mathematica. What I'm trying to do is create a matrix with elements inside. ...
4
votes
0answers
62 views

Eigensystem on HPC

I am submitting Mathematica jobs to an HPC. I have a large matrix that is a function of (x,y) and I am diagonalizing it for around 500 points in the plane. My initial idea was to request a node with ...
4
votes
1answer
453 views

Over 30mins to generate the first eigenvector?

Is it normal for Mathematica to take over 30mins to try to compute the first eigenvector of a 100x100 matrix? The matrix is reasonably sparse - about 90% of the cells are 0s and each column sums to ...
1
vote
1answer
72 views

How to form a variable from matrix elements

I have matrix with n rows and 2 columns, say m = {{x11, y12}, {x21, y22}, ..., {xn1, yn2}. Now, I want to form three new variables for example: ...
0
votes
1answer
59 views

Submatrix with linearly independent columns

What I want is the submatrix where all the linearly dependent rows have been eliminated. I tried implementing this solution, but it doesn't work in the following example: ...
0
votes
0answers
43 views

How to display a list using numerical values? [duplicate]

Suppose I compute the eigenvectors of a matrix like this Eigenvectors [{{3, 2, 3, 1}, {2, 3, 1, 1}, {0, 0, 2, 1}, {2, 3, 2, 1}}] The result I get looks like: ...
2
votes
1answer
221 views

Quick way to tell if matrix is integer-only?

What's the most shortest one-liner code to tell whether a matrix is integer-only? I've come up with: Length@Cases[A // Flatten, _?(Not@*IntegerQ)] == 0 but ...
1
vote
2answers
39 views

Exporting mixed data of matrices and vectors / lists

thank you for reading my question. I have a problem trying to export mixed data from Mathematica. I have different matrices and vectors, which should be combined to a output file. Here a ...
2
votes
1answer
129 views

Neighbourhood - Calculations

SeedRandom[0]; n = 5; (m = N @ RandomInteger[{1, 3}, {n, n}]) // MatrixForm result1 = MeanFilter[m, 1] // MatrixForm ...
0
votes
0answers
10 views

Is there any direct method for Lagrange multiplier based domain decomposed problem? [migrated]

In elastic problem, we often solve K * u = f, where K is the stiffness matrix, f the external force vector and u the displacement vector. I'm trying decompose the mesh to domains, using Lagrange ...
12
votes
5answers
3k views

Division by zero is slow

Suppose I have two arrays of data, which I want to divide: ...
1
vote
1answer
102 views

how to diagonalize this symbolic matrix?

m = {{0, 0, w}, {0, t, -w}, {w, -w, r}} use equation P^(−1)A P, how to obtain P with Mathematica? Thanks!
3
votes
1answer
90 views

An efficient way to compare two matrices

I have two matrices mat1 and mat2, both are results from different algorithms that are supposed to calculate the same result. The nmax is around 300, the q varies from 0.001 to 1. ...
5
votes
4answers
229 views

How to extract a part of matrix satisfying certain condition(s)

I have a following matrix ...
2
votes
0answers
27 views

Automatically discover the class of an arbitrary matrix

In Wolfram|Alpha it is possible to discover some specific classes to which a matrix belongs. For instance, typing this in Wolfram|Alpha ...
4
votes
3answers
100 views

A Product function for matrix products

I would like to use an equivalent of the product-function in mathematica, but where instead of multiplying numbers I multiply matrices?
0
votes
1answer
45 views
1
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0answers
53 views

Programming for matrix manipulation

I want to write a programme which operates on nd x nd matrices. The programme looks the matrix as a n x n block matrix where ...
2
votes
2answers
45 views

Returning the 3-dimensional vector from a skew symmetric matrix

I'm trying to write a function that takes in a skew symmetric matrix and returns the corresponding vector. When I write the following code, it works when I leave it as variables, but it does not work ...
0
votes
1answer
41 views

Display problem multiplying matrix [duplicate]

I'm multiplying matrices and I don't get answer I want I just get matrix M times matrix N, there is no result. What to do and ...
1
vote
0answers
99 views

Replace part in a matrix that matches specific pattern

I have the following problem. Given a matrix L which looks as follows, Matrix L is a link, route matrix. Further, I got the following vector (d), which indicates the demand per vertex combination. ...
3
votes
0answers
48 views

Calculation the eigensystem of a matrix containing very small numbers

I'm dealing with a matrix containing very small numbers like 10^(-370). Whenever I'm trying to calculate the eigensystem of that matrix, it takes too much time, though the matrix size is not big that ...