Questions on the manipulation of matrices in Mathematica.

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3
votes
2answers
110 views

Help with building matrices

I am a complete beginner in Mathematica and I have a small problem. I have this three matrices (A,B and C) and with them I have to build larger matrix M which looks like this. What would be the ...
2
votes
0answers
242 views

Fast export of large numerical data

Edit It seems that the bottelneck is not due to eigen value problem. I will esit the question soon. I have a 6000by6000 matrix which I got after some calculations. I want to get the eigenvalues and ...
1
vote
2answers
95 views

how to get continuation of square matrices with periodic diagonal band automatically?

I want write a function that can automatically analyze any square matrices with periodic band diagonals and give continuations of them. But I can't figure out an elegant way to do this. Suppose we ...
2
votes
1answer
139 views

Anyone knows the algorithm used by NullSpace function?

NullSpace function gives a list of vectors that forms a basis for the null space of the input matrix. When the rank of the input argument matrix $M_{m\times n}$ is ...
2
votes
3answers
593 views

How to find the kth largest eigenvalue of a matrix, taking into account the sign? [duplicate]

I have a real symmetric matrix m (i.e. its eigenvalues are all real). Eigenvalues[m, {k}] will find the ...
1
vote
2answers
518 views

Get inverse of a matrix step-by-step [duplicate]

How can I get the inverse of a matrix step by step? An example: Given the matrix `{{8, 2}, {3, 2}}´, the result is {{$\frac{1}{5}$, -$\frac{1}{5}$}, {-$\frac{3}{10}$, $\frac{4}{5}$}}. But how can I ...
1
vote
1answer
528 views

How to add an extra column to a current matrix (list)? [duplicate]

a = {{-800, 1712}, {-801, 1713}, {-806, 1832}} TableForm[a] b = a[[All, 2]] - Min[a[[All, 2]]] How do I make a new matrix (list) whic looks like this ...
3
votes
0answers
158 views

The CorrelationMatrix is equal to corrcoef of Matlab?

How can I generate a matrix which is equivalent to the results of the "correlation coefficients" command (corrcoef) in Matlab? When I make a LinearModelFit, I can get a CorrelationMatrix, but is this ...
1
vote
1answer
266 views

Correlation to Covariance Matrix

I am looking to use the CopulaDistribution fucntion, with a "MultiNormal" kernal. However, for the input, O require a covariance matrix. However, I only have a correlation matrix. Is there a way to ...
1
vote
2answers
145 views

Table operation after export and import of data does not give me the same result

If I create a table of this kind: (m1 = Table[{RandomInteger[], RandomInteger[{1, 5}, {3}]}, {i, 1, 5}]) // MatrixForm which looks like I know how to pick ...
3
votes
2answers
139 views

Eigenvectors of large symbolic matrix

I have large symbolic matrix of order 32 x 32 given as ...
2
votes
0answers
227 views

Best way to create symmetric matrices with block structure and additional symmetries of the submatrices

Update: you can now skip the "My attempted solution" part and jump to "My first attempt for improvement" in the end of the question. My question is related to Best way to create symmetric matrices . ...
0
votes
1answer
82 views

How to use Hold on a variable defined as a graph

I'm working on doing operations on different graphs and getting their probability node degree distributions using a simple algorithm. If I have many defined graphs, for example: ...
2
votes
2answers
113 views

Findings rows in RREF matrix which contain nothing but a pivot

I am asked to find all rows in a matrix in reduced row echelon form which contain nothing but pivots (pivot is $1$, all other entries are $0$). For example, in this matrix: $$ \begin{bmatrix} 1 ...
1
vote
0answers
50 views

Dealing with answers that have Root[ …] when finding an Eigensystem [duplicate]

This is a 3x3 matrix and I think it should solve for the expressions in terms of radicals. I am not sure what to do with this.
-2
votes
1answer
62 views

Create a matrix by crossing a list

I've a list L of elements. I want to create a matrix by laying each elements of L in both rows and columns where each ...
1
vote
3answers
159 views

Matrices and Combination

When the positive integers 1 to 9, inclusive, are used exactly once as elements of a 3 x 3 matrix, what is the largest possible value of the determinant of the matrix?
0
votes
1answer
37 views

dropOperator done on Matrix of a Matrix - How is this done?

I have implemented this dropOperator from dropOperator from stackexchange and works fine on a single Matrix. But now I have a Matrix of a Matrix and want to drop some rows or columns (in the pic below ...
0
votes
2answers
188 views

Block matrix definition and inversion

I would like 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 & ...
1
vote
1answer
152 views

How to print non zero elements of the matrix containing zero elements and non-zero elements both?

A matrix with both non-zero and zero elements is given. I want to print only the non-zero elements of the matrix. What is syntax that have to be used for this? matr2 = Table[FortranForm[matrixx[[i, ...
2
votes
2answers
152 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? ...
1
vote
2answers
117 views

How to extract matrix which produces given symbolic linear combinations?

Suppose I have a column matrix $\alpha$, consisting of some symbols ...
1
vote
1answer
87 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
110 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". ...
1
vote
2answers
53 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: ...
3
votes
2answers
281 views

Understanding polyharmonic splines

Rahul Narain and J.M. gives implementation of the thin plate polyharmonic splines in this post. Rahul Narain's method is clear. J.M.'s is convenient to reuse. But J.M. used too many ...
0
votes
1answer
136 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 ...
2
votes
2answers
362 views

Logarithm of a matrix in base 2?

Mathematica provides the built-in command MatrixLog, which operates on a square nonsingular matrix, but it returns the natural logarithm. How can I find the base 2 ...
2
votes
1answer
92 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
vote
0answers
49 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. ...
3
votes
1answer
152 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
219 views

matrix multiplication speed

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

Suggest how to do this matrix multiplication [duplicate]

Have a look at the Mathematica calculation ...
1
vote
1answer
145 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
45 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
2answers
98 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
138 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
177 views

Matrix multiplication

I want to multiply 1000by1000 matrices but MMA runs out of RAM. ...
3
votes
4answers
178 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
124 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
1answer
362 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
1answer
134 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 ...
5
votes
1answer
492 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
93 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: ...
1
vote
3answers
157 views

Randomly changing matrix entries

Write a block of code that generates a 4x4 matrix with randomized real number entries each between 0 & 1, then selects 3 matrix entries at random, and finally replaces these 3 entries with ...
0
votes
1answer
110 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: ...
2
votes
1answer
233 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
64 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
146 views

Neighbourhood - Calculations

SeedRandom[0]; n = 5; (m = N @ RandomInteger[{1, 3}, {n, n}]) // MatrixForm result1 = MeanFilter[m, 1] // MatrixForm ...
14
votes
5answers
3k views

Division by zero is slow

Suppose I have two arrays of data, which I want to divide: ...