Questions tagged [matrix]

Questions on the manipulation of matrices in Mathematica.

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4
votes
5answers
368 views

Need Help Writing (a Pascal) Matrix in Mathematica

I want to write a function $f[n]$ in Mathematica which gives me an $n\times n$ lower triangular Pascal matrix with a row of zeros in between each nonzero row. That is, I want the matrices \begin{...
4
votes
2answers
1k views

Exact cover solution

Is it possible to get a exact cover solution(s) and/or number of possible solutions in Mathematica?
5
votes
1answer
266 views

What's wrong with this code to create a matrix?

Here is my code: ...
6
votes
2answers
2k views

Sort matrix by columns and rows without changing them

I would like to sort a matrix in descending order first by the total of each column, then by the total of each row, but without changing their content. For example, if I had: ...
3
votes
2answers
410 views

A lot of matrix multiplication

So I have a set of 15 $4\times 4$ matrices which I call $X_i, (i=1,2..15)$ and a set of 6 $4\times 4$ matrices which I call $y_j, (j=1,2...6)$. Now I have to calculate $(X_i y_j)-(y_j X_i^*)$ for ...
7
votes
4answers
6k views

I need to multiply a series of matrices

I need to perform a dot product on a large number of 2 x 2 matrices that I have defined to differ by even/odd subscripts (Ex: D-odd=x but D-even=y). The $\Pi$ function will not work because it does ...
14
votes
3answers
2k views

How to manipulate gauge theory in Mathematica?

I want to know if there is a way of typing into Mathematica an expression like the following, $$\epsilon^{\mu \nu \lambda} f^{abc} A^a_\mu A^b_\nu A^c_\lambda + g\epsilon^{\mu \nu \lambda} A^a_\mu \...
7
votes
4answers
238 views

Generating all matrices with 1 (possibly) replaced by -1

I have a matrix $M$, whose dimension I am unsure of, which has only $\lbrace0,1\rbrace$ entries. I would like to generate all the possible matrices that result from changing (some subset) of the $1$'s ...
3
votes
4answers
413 views

Are table headings functional?

Are table headings for aesthetics only? For example, if I have: ...
1
vote
1answer
184 views

Optimization of correlation calculation

How can I make the following line of code run faster? Is there a way to do this calculation as a matrix vs vector than vector vs vector? In the code below, f is a ...
3
votes
1answer
847 views

Find an inverse matrix, regarding a parameter as real

I have the matrix ...
3
votes
1answer
756 views

How to modify a matrix to satisfy a special condition?

I have matrix like this: How do I modify this matrix to make it satisfy the following condition: For each element {i, j} in the matrix the sum of the elements of row i must be equal to the sum of ...
3
votes
2answers
734 views

Eigensystem, Eigenvalue doesn't output nonreal eigenvalues

Basically I have a matrix and when I used either Eigenvalue or Eigensystem, it doesn't output nonreal eigenvalues, instead it ...
4
votes
6answers
514 views

Sorting Matrix elements

I have matrix in as shown, consisting of real numbers and 0. How can I sort it to become out as shown? ...
6
votes
3answers
869 views

How to sum matrix elements based on finding the first (and second) non-zero elements of each row?

I have a matrix: I would like to sum all the first non-zero elements of each row so that I get a value of $$25.5317 + 8.85471 + 6.90018 + 32.9436 + ... $$ and so on and simply ignore zero rows. ...
0
votes
0answers
41 views

Why isn't the matrix product computed? [duplicate]

Possible Duplicate: Why does MatrixForm affect calculations? I have the following input: http://wstaw.org/m/2012/11/15/geogebra4.png Why is the matrix not computed, giving me a $2 \times 2$ ...
1
vote
1answer
848 views

How to Sort on row by row basis?

Say I have matrix how to sort on row by row basis to get:
1
vote
1answer
595 views

How to do conditional matrix division when elements are a combination of zero and real numbers?

I tried to divide two large matrices DLand PL of size 100,000 x 5 each and they look like this, DL= and PL= By using conditional function: ...
2
votes
1answer
726 views

Solving a system of PDEs expressed in matrix notation

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1
vote
2answers
1k views

How to take matrix elements as input to another matrix or loop?

Say I have matrix tmp1 of size 1000 x 5 (shown is just a small section for illustration purpose), consisting of real numbers and 0: How can I iteratively take every non-zero real number elements and ...
0
votes
2answers
153 views

Matrix conditional operation

Say I have a matrix of: tmp1 = 5; tmp2 = 5; tmp3 = RandomChoice[{0, 1, 2, 3, 4, 5}, {tmp1, tmp2}]; MatrixForm[tmp3] How to do a conditional operation of elements ...
0
votes
2answers
311 views

How to get a sub range of a larger matrix?

This should be an easy question but I only found a partial solution using All. Say I have a matrix A = 1000 x 5, how to get only a part of that matrix, say B = n x ...
2
votes
3answers
507 views

Is there a way to do conditional matrix loop using 'continue'

I have the following: ...
2
votes
1answer
329 views

Rearranging a biclustered matrix

I currently have a $77\times 38$ matrix, and I have used a clustering algorithm to cluster the row data and column data. The rows and columns of my matrix correspond to a list of country codes (not in ...
1
vote
1answer
2k views

Matrix Multiplication Modulo 2

I would like to perform matrix multiplication modulo 2. Hence, instead of the usual: A.B I did: ...
1
vote
3answers
393 views

How to do equality check of a large matrix and get the corresponding index position?

Say I have a matrix A = 1000 x 5, and I want to compare it's first element (uppermost top left) to each of the 5 elements in the first column of matrix B of size 5 x 5. Whenever the first time the ...
0
votes
1answer
645 views

using Mathematica's matrix multiplication in C++

Is there any way that I can utilize Mathematica's matrix multiplication in a C++ program? I'm making a 3D graphics engine (for class) in C++ and I would really like to use Mathematica for all of my ...
3
votes
0answers
254 views

Mathematica Complains about Non Symmetric Covariance matrix, when it's not the case

I was doing some fitting with Mathematica7 using NonlinearModelFit. It's quite long the program to do the fit and that's why I am not displaying here ... It goes ok, and I can get the fit parameters ...
0
votes
1answer
236 views

how to get modify the following correlation matrix with a specific list of financial prices?

The following takes the last 5 members of the Dow Jones index and plots the correlation matrix of the last 5 years of daily prices: ...
2
votes
1answer
1k views

Tridiagonal matrix for any n

I'm pretty new to Mathematica and I need to figure out how to create a $n\times n$ tridiagonal matrix for any $n$. I don't have the slightest clue where to begin. Edit: got this far, not sure how to ...
11
votes
3answers
658 views

How do we solve N-Rooks variation using primes?

Using a $p_n $x $p_n$ matrix, how can we solve the N-Rooks problem to find a prime in every row and column? ...
2
votes
1answer
544 views

Can mathematica simplify an expression setting simplified answer equal to zero?

Basically I want to reduce something like: Subscript[P, 4] - Subscript[P, 5] == Subscript[R, 4, 5]* Subscript[i, 4, 5] when only one of them is known (...
2
votes
1answer
735 views

Creating a matrix from the output of a variable inside a for loop

I would like to enter the results of the following loop inside a matrix as its elements: ...
1
vote
2answers
2k views

How to calculate FDCT

I'm new to Mathemtica and I'm trying to calculate Discrete Cosine Transformation FDCT. I found the FourierDCT built-in function, but not DCT, so I need to implement it. I have tried couple of ideas ...
1
vote
1answer
1k views

Calculating an exact orthogonal modal matrix in Mathematica

I can calculate the modal matrix of a matrix A using the command JordanDecomposition[A][[1]], and a decimal approximation of the orthogonal (or normalised) modal ...
3
votes
2answers
2k views

Subspaces in Mathematica

I'm working on a research project and I need to learn how to use Mathematica to calculate subspaces. Specifically I plan to solve the following operations and I would greatly appreciate if you could ...
4
votes
1answer
364 views

Printing Block Matrices

I have a 2D matrix, such as: d=2; M=Array[a, {d^2,d^2}]; and I would like to print it in a way which emphasizes its dxd block matrix structure. If ...
6
votes
2answers
3k views

Eigenvalue / Eigenvector Calculation

I'm currently trying to compute the three smallest eigenvectors for a 34 by 34 matrix. While I was expecting this to take some time, Mathematica has been running for the past 3 hours, which seems ...
2
votes
5answers
232 views

Test First row of matrix

What is a good way to test the first row of a Matrix to check if one of the values equal a value. For instance, In this example, I want to get vector in the second row that has the bigger value in the ...
5
votes
2answers
670 views

Loop and do operations on Matrix, then graph the results

I'm trying to do some operations to a matrix in a loop, and then I want to graph the results. The results are pair of numbers. Can I store the results of each iteration on "something" and the use ...
4
votes
2answers
1k views

Total Variation Distance of probability matrix

How can I calculate the Total Variation Distance of a transition Matrix? is there any built in function? I've searched all documentation and haven;t found anything. ** More information: Let me try ...
4
votes
2answers
551 views

Transform x-scale of data for e.g. MatrixPlot

I have to transform in a nonlinear way the x-scale of some data for a MatrixPlot (or ReliefImage or ...
2
votes
1answer
378 views

Numerical comparisons of matrices

I have a matrix which should be equal to a null matrix. However due to the numerical precision, a brutal equality test with a matrix initialized with zeros does not work. How should I perform the ...
4
votes
1answer
2k views

stationary distribution of a transition matrix

How can I solve the stationary distribution of a finite Markov Chain? In other words, how can I estimate the eigenvectors of a transition matrix?
10
votes
1answer
5k views

Mathematica won't give eigenvectors but Wolfram Alpha will? What am I doing wrong?

If I ask Mathematica to find the eigenvectors and eigenvalues of the matrix: ...
4
votes
1answer
3k views

Creating a random normal matrix

I would like to create a random matrix with the constraint that the matrix must be normal, i.e. the matrix and its Hermitian conjugate must commute. I would create a random matrix "without constraints"...
12
votes
4answers
371 views

Inputting a big structured matrix in Mathematica

Hi this is my first post and this is a problem that has bothered me a lot. Suppose we have the $2012\times2012$ square matrix: $\begin{bmatrix}-3&1&1&1&1&1&\ldots&1&1&...
12
votes
1answer
1k views

How to extract and replace submatrix of a doubly-periodic matrix?

How can I effectively extract and replace a rectangular subpart of a toroidal matrix, i.e. one where boundaries are connected at opposite ends? Since the submatrix can overhang the edges, a simple <...
13
votes
2answers
587 views

How can I compute the representation matrices of a point group under given basis functions?

Take the $C_{3v}$ point group for example: ...
2
votes
3answers
3k views

Finding eigenvalues of a $1500\times1500$ matrix

I need to find the eigenvalues of a $1500\times1500$ real symmetric matrix given by $A_{i,i+1}= A_{i+1,i}=-1$ and also $A_{1,N=1500}=-1$ (this is because of a periodic boundary condition used) and all ...