Questions on the manipulation of matrices in Mathematica.

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1
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1answer
153 views

finding eigenvectors of a n*n symbolic matrix [closed]

is it possible to find eigenvectors and eigenvalues of this matrix in mathematica?i have no idea about solution!please help... ...
1
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1answer
113 views

How to simplify symbolic matrix multiplication using the associativity of scalar multiplication?

My input is (2A).(3B). Is there a way to get 6A.B? All I could get back from Mathematica was ...
6
votes
2answers
263 views

How to transform a matrix to upper-triangular with operation- tag elegantly?

Description: Recently, I have a thought that writing a function to show the transformation process when a matrix is transformed to upper-triangular. My trail ...
1
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1answer
101 views
0
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1answer
65 views

Solving at zeroes of a matrix - code only works for simple equation

I have a matrix of zeroes (True) and non-zeroes (False). The matrix is generated from a table of values of two other variables. I'm trying to observe how the solution for p3 changes with small ...
5
votes
3answers
108 views

SingularValueDecomposition outputs unsolved Root expressions [closed]

I have a simple 4x10 matrix of real integers (It's a Vandermonde matrix for x=1,2,...,10, if that's relevant) that I'm trying to do SVU decomposition on. When I use the SingularValueDecomposition ...
3
votes
6answers
171 views

Change last column of a matrix

Given a (rectangular) matrix of integers, i.e. RandomInteger[4, {10, 3}] I want to apply the following rules only to the last column ...
6
votes
3answers
161 views

Remove Successive Duplicate From A Large List (200k by 4 matrix)

I am interested in removing successive duplicate rows from a very large list (~200k rows by 4 columns) using Mathematica.The built-in 'DeleteDuplicates' seems to remove all duplicates, I am interested ...
8
votes
2answers
327 views

How to add a vertical line to a matrix?

Today, I want to write a program to show the solving process of a the inverse of a matrix, and I use the Elementary transformation, so I need to add a vertical ...
7
votes
3answers
298 views

Need help with plotting triple data points while xy data are not regular?

recently I plotted some figure in matlab whose quality is not so satisfactory, so I come to mathematica as my supervisor suggested. This is how it looks like in matlab:. In matlab I have three m by n ...
0
votes
0answers
36 views

Numerical Error with Matrix operations

A is a 3x3 matrix, b is a 3x1 vector. I try to convert [A|b], a 3x4 matrix, to [I|0]. So the formula is right multiple ...
1
vote
2answers
94 views

Verify positive definiteness using random numbers

I wish to verify whether T'T - IdentityMatrix[2] is always positive definite for a certain choice of elements of T'T. ...
8
votes
3answers
300 views

Random Integer Sequences

I want to construct a random square matrix in the following manner: a) Three states [0 | 1 | 2] are repeated ...
2
votes
1answer
355 views

An intuitive way to form an augmented matrix

Given an $m\times n$ matrix $A$ and a $m\times 1$ vector $b$, what is the most "intuitive" way of forming the augmented matrix $[ A\ b]$? The most concise way that I know of is ...
3
votes
1answer
68 views
1
vote
1answer
263 views

Dirac Gamma matrix Algebra in different dimension

Do anyone know if we could do Dirac Gamma Matrix Algebra by FeynCalc with Gamma Matrices defined in different dimension than 4, e.g. DiracTrace of gamma matrices in 2+1 dimension? Thanks!
1
vote
0answers
31 views

Symbolic computation under certain assumptions [duplicate]

Assume that I have a matrix $M$ and I'm doing some operations on it. Is there a way to specify that two variables satisfy an equation say $x=y^2$ and then let Mathematica compute under that ...
5
votes
3answers
414 views

Visualization of matrix transformations

I define the "matrix transformation" here as follows: $\left[ \begin{matrix} x_1' \\ x_2' \\ \end{matrix} \right]=\left[ \begin{matrix} a & b \\ c & d \\ \end{matrix} ...
1
vote
1answer
98 views

sequence of matrix multiplications

My linear algebra book has questions that are are marked to use math software. There's probably some $50 guide on how to do everything but usually documentation has gotten me through. I've been kind ...
62
votes
2answers
2k views

Flatten command: matrix as second argument

One thing I could never wrap my head around is how Flatten works when provided with a matrix as the second argument, and the Mathematica help isn't particularly ...
4
votes
1answer
158 views

Calculate the covariance of a large matrix

I have to compute the covariance of 50 very large integer matrices (2500x2000 elements). However, according to my estimation this will take around 10 days. Do you have any ideas how to speed things ...
14
votes
2answers
421 views

Better way to test that a matrix is upper-triangular?

Today, I got to thinking about how to test that a matrix was upper-triangular. So I had a try at it. Algorithm $\quad \quad a_{ij}=0 $ Or $i \leq j$ $\Rightarrow$ $True$ My solution is ...
2
votes
3answers
135 views

How to multiply specific columns in a matrix of data?

So I need to make a plot of some ~2000 data points I have from a spreadsheet. I'm able to import the data just fine, it stores it like so sundat ...
9
votes
3answers
910 views

An inverted pyramid

I want to draw a pyramid approximately like this ...
6
votes
3answers
241 views

Efficient method to generate Tridiagonal 50 by 50 Matrix? [duplicate]

I'm looking to generate a tridiagonal 50x50 matrix, ideally without using loops. Suggestions on most efficient code for this?
3
votes
1answer
123 views

Why does LinearSolve return the transpose of the answer matrix?

I am trying to solve an equation of the form $dv=F\cdot dV$ where $dv$ and $dV$ are matrices derived from the row vectors $dx$, $dy$, $dz$ and $dX$, $dY$, $dZ$ respectively. If it helps, $F$ is the ...
33
votes
6answers
2k views

How to visualize/edit a big matrix as a table?

Is it possible to visualize/edit a big matrix as a table ? I often end up exporting/copying big tables to Excel for seeing them, but I would prefer to stay in Mathematica and have a similar view as in ...
2
votes
3answers
222 views

Syntax of transpose etc [closed]

This is a simple question: {{0, 1}, {0, 2}, {0, 3}}*Transpose[{{0, 1}, {0, 2}, {0, 3}}] returns an error in Mathematica but works perfectly fine in Wolfram Alpha. Can someone help me? Thanks so ...
9
votes
4answers
298 views

Replacing matrix values

I want to find the n largest values in a matrix and replace all others with zero. The solution I found uses ReplaceAll and becomes very slow as the size of ...
1
vote
1answer
120 views

Inverting matrix of unknown size

I have a matrix that has a variable number of columns and rows (but it is always square). The matrix is: $$ \Gamma = \begin{bmatrix} \Theta & 0 & 0 & 0 & T & 0 & R_j \\ ...
1
vote
2answers
1k views

large matrix eigenvalue problem

I need solve a very large complex matrix (not sparse and not symmetry) eigenvalue problem, e.g., 1e4*1e4 or even 1e6*1e6. How large dimensions of the matrix can Mathematica support? And, how about ...
6
votes
3answers
146 views

How to create a block diagonal matrix by repeating a submatrix $n$ times?

If there is a submatrix, let's call $P$: $P=\begin{pmatrix} 1 & 1 \\ 1 & 1 \end{pmatrix}$ And I want to have $n$, let's say $n=2$, such submatrices placed on the diagonal. The result is ...
3
votes
0answers
150 views

Fast principal component analysis

I'd like to speed up a principal value value analysis. The data contains a large set of vectors with a large dimension. Both are in the range of 1000. I want to obtain the loadings matrix for further ...
0
votes
1answer
57 views

Combining lists in a matrix

So I have a list of data A={1.1,1.2,1.3,1.4,6.1} etc and B={2.5,2.6,2.7,2.8,2.9} I need to combine the lists into a matrix C ...
4
votes
1answer
148 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 \\ & &{} + ...
2
votes
3answers
199 views

Hypergeometric function with a matrix argument

I am looking for the evaluation of a Hypergeometric function with a matrix argument as for example in Ploev and Edelman or as showcased in this Wikipedia article. From what I understand from ...
0
votes
6answers
219 views

How to build a game board [duplicate]

I have - rather lazily - constructed a chessboard like this: ...
3
votes
2answers
254 views

Order of eigenvectors [duplicate]

I have a matrix A = {{5, 4, 2}, {4, 5, 2}, {2, 2, 2}} The eigenvalues are 1, 1, 10 and I need to find the eigenvectors. ...
1
vote
1answer
73 views

m equations and n variables. Reducing using Mathematica

I have six equations and thirteen variables. I would like to reduce it to seven free parameters. I used Reduce to solve it but it is taking really long (one full day and no output yet) and I think ...
3
votes
2answers
327 views

How to create a 'shortest-path link matrix'?

I am currently struggling with a problem in Mathematica. I have a randomly generated weighted Barabasi-Albert graph and a corresponding demand matrix of the same size. I'm generating the graph with ...
15
votes
1answer
313 views

Unpacked eigenvectors of complex matrices

Edit: This bug is fixed in Mathematica 10.0.0 I want to calculate eigenvectors of a Hermitian matrix. For example ...
0
votes
1answer
181 views

Defining a new matrix product of matrix function [closed]

Suppose I have two matrices A, B, whose entries are functions of x. Suppose they are 2*2. In the product, each entry is of the form $\sum_k A_ik B_kj$. There are two summands corresponding to k=1,k=2. ...
3
votes
3answers
136 views

Solving determinant of a Kronecker product of matrices gives a numerical error - why?

I am doing the following steps (code at the end of the post): I start with a 2x2 matrix (smatrix), which is a function of a single variable (u2). I want to set the determinant of this matrix ...
5
votes
2answers
1k views

How do I keep the right ordering of eigenvalues using Eigensystem?

I'm having an issue with the Eigensystem command. I need to diagonalize a bunch of 3 by 3 complex valued matrices, but more importantly, I need to keep the exact ...
4
votes
3answers
157 views

Split matrix by all-zero columns

Below is my input: mat = {{0, 0, 0, 0, 0, 1}, {1, 0, 0, 1, 0, 1}, {0, 1, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 1}, {1, 1, 0, 1, 0, 0}, {0, 0, 0, 1, 0, 1}}; ...
14
votes
4answers
691 views

“Indexing” a vector

I need to "index" a vector according to the first occurence of its distinct elements. I have written ...
2
votes
2answers
113 views

Making a conjecture concerning a certain upper-triangular matrix

I have searched for commands which will let me to create matrices and do matrix operations, but I don't know how to apply Mathematica to the following exercise. Make a conjecture for the result of ...