Questions on the manipulation of matrices in Mathematica.

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6
votes
2answers
133 views

Good way to create a similarity / distance matrix for a large dataset [duplicate]

I have a large dataset with rows (100k+) for products and columns for features. Now I want to create a similarity matrix with NormalizedSquaredEuclideanDistance. ...
0
votes
0answers
48 views

Value Iteration (Recursive iteration) to Minimize (Optimize) a Function

I have a function that I call as "Value". I am trying to find the minimum of this function and this function is a function of 4 other functions. One of these four functions is recursive based on the ...
1
vote
1answer
154 views

How do you solve a linear equation of matrices? [duplicate]

The function Solve works fine for scalars: In[]:= Solve[A x - x B + C == 0, x] Out[]= {{x -> -(C/(A - B))}} When using matrices however, ...
2
votes
1answer
40 views

Square bracketed matrices in Mathematica - precision markers?

I'm trying to display Matrices with square brackets in Mathematica. I've found this post from a mailing list in 2009 http://forums.wolfram.com/mathgroup/archive/2009/Aug/msg00458.html and it seems to ...
6
votes
1answer
137 views

Calculate the ESP Grid based on Density Grid

I want to build a fast way to convert a density grid file into a grid file of the respective electrostatic potential (ESP; also known as MEP, the molecular electrostatic potential). This ...
5
votes
4answers
451 views

How to simplify block of multiple repetitive If statements?

I'm building a boardgame...game in Mathematica. I have the board state represented as a matrix. It's a two player game, and each player (let's call them A & B) only has one type of piece or '...
0
votes
2answers
91 views

I'm trying to solve a system of complex equations

I'm simply trying to solve a system of equations and mathematica can't do it for all values over the region of interest. I have a 3x3 matrix that has a specific parametrization and after squaring the ...
1
vote
2answers
95 views

Plot values of an $m\times n$ matrix on the complex plane with color varying along $m$

Let's say I have a complex valued matrix $\begin{pmatrix}1+I&2+2I&3+3I\\4+4I&5+5I&6+6I\end{pmatrix}$ represented by a list: ...
11
votes
9answers
768 views

Forming an upper triangular matrix from the elements of a list

I asked this question before, but i was closed because it the question was not comprehensible enough. So i reworded it, hope that's ok. I have a list with 6 elements. ...
1
vote
0answers
45 views

Generating random Kraus operators

I am trying to generate (randomly) set of square matrices $\{K_m\}$ with the properties that $$\sum_{i=1}K_i^{\dagger}.K_i=I_n,$$ where $I_n$ is the identity matrix of order $n$. So, the input should ...
0
votes
1answer
32 views

Iterating KroneckerProduct[] and returning the result from a function

I am trying to write a function which will take a matrix m and an integer i as inputs. Then it will compute the Kronecker product of m with itself i times and return the result. The code is as follows....
2
votes
1answer
66 views

Accuracy limitations of singular value decomposition?

in the process of working on a physics problem I have found the need to use the singular value decomposition function built into Mathematica. I have encountered what seem to be limitations to the ...
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.
1
vote
0answers
149 views

Request for clarification of Eigensystem::eivn message

What causes the problem of "two eigenvectors associated to one single multiplicity eigenvalue" that I am experiencing? After several transformations to simplify an unwieldy matrix, I end up with the ...
0
votes
0answers
99 views

Is Eigensystem::eivin message a bug?

I noticed that in the question Request for clarification of Eigensystem::eivn message the error message Eigensystem::eivn: Incorrect number 2 of eigenvectors for eigenvalue Root[<<14>>+(<&...
0
votes
1answer
88 views

How to get rid of # in answer (eigensystem)? [duplicate]

I was trying to find the eigensystem of the following matrix (act as if the second character is in subscript): \begin{pmatrix} 0 & 0 & 1 & 0 \\ 0 & 0 & 0 & 1 \\ \frac{-\...
6
votes
4answers
3k 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 ...
0
votes
0answers
29 views

factoring a phrase of matrix elements and calculating main eigenvalues

I have a question containg two parts: 1-If we have a matrix as ...
0
votes
1answer
50 views

Inverse of a Fourier matrix [closed]

I am trying to find the inverse of a Fourier matrix but I am getting confusing results. If R is a Fourier matrix, then ...
6
votes
3answers
327 views

Indicate minimal path sum

Described on the page: http://www.mathblog.dk/project-euler-81-find-the-minimal-path-sum-from-the-top-left-to-the-bottom-right-by-moving-right-and-down/ It is an example of the solution indicated in ...
0
votes
1answer
49 views

How to pad numbers to the border of the Matrix?

I want to pad the numbers,but it throws an error Part::partw,so I use Quiet to suppress this error. ...
0
votes
4answers
51 views

insert elements into 2 D array [duplicate]

say I have a 2 dimensionsal array like a={{1,2,3},{4,5,6},{7,8,9}} and a vector like v={10,11,12} I want the result to be ...
1
vote
0answers
47 views

Working with matrix

Considering the 3x3 matrix: m = {{0, -(I/Sqrt[2]), 0}, {I/Sqrt[2], 0, -(I/Sqrt[2])}, {0, I/Sqrt[2], 0}} How would I find its normalized vectors eigenvectors u_i ...
3
votes
0answers
69 views

Why does Eigenvalues work for a matrix $\{M\}$ but not $\{\{M\}\}$?

Suppose I have a matrix {{1, 2}, {3, 4}} which I'll call mat. In a blur of human error, I computed the eigenvalues of ...
0
votes
1answer
92 views

How to turn a subroutine into a function?

I've written a subroutine that takes in 6 matrices and after some manipulation returns back 3 new ones. I will use this subroutine fairly often in this notebook so I think it would be easier to turn ...
-1
votes
1answer
64 views

Real and Imaginary matrix

I have a 2 by 2 matrix T: {{x, y}, {-y, x}} where x is the real part of some complex number and y is the imaginary part of something complex number. Let's say z1 = ...
1
vote
0answers
39 views

Getting the row/column reduction matrix of a matrix m

Is there a simple way to get the row reduction matrix for a matrix m? As in, a matrix a such that ...
2
votes
0answers
68 views

Unexpected behavior from applying ToRadicals to eigenvalues [closed]

I am trying to get the symbolic form of a $10 \times 10$ matrix (I know, that is generally too large). ...
5
votes
3answers
244 views

Assumptions for RotationMatrix

I'm making C++ program, and in my program I need a rotation matrix around any vector. I wanted to extract RotationMatrix[fi,{x,y,z}] output and put it in my program....
3
votes
0answers
83 views

Real Canonical Form of Arbitrary Size Matrices

I have been searching the site and the Mathematica documentation, but have not found anything regarding this. If we find the Jordan Form of the following matrix, we get complex values, but I would ...
1
vote
0answers
97 views

Outer product using the quantum mathematica package

I am using the quantum Mathematica package and am trying to do computations that require me to use the outer (tensor) products of Pauli matrices. I would define this as, for example, ...
1
vote
2answers
63 views

Trouble implementing logarithmic matrix norm

I wanted to write a quick function that calculates the logarithmic matrix norm with respect to the spectral norm. The formula is $$ \mu_2(A) = \lambda_\mathrm{max}\left(\frac{A + A^T}2\right). $$ So ...
2
votes
0answers
45 views

Optimization for iterating and plotting a matrix product and its elements?

I have an iterative matrix product of this type Since i didnt knew how to do it, I explicitly wrote the product as {Ayn + Bxn, Cyn + Dxn} and evaluated it with the NestList construct ...
11
votes
4answers
486 views

How do I extract a matrix of only positive numbers given a set of assumptions?

I want to divide a matrix: mat = {{a, 0, -b}, {d, a, 0}, {0, 0, -a}} with the following assumptions: ...
0
votes
1answer
50 views

Overriding Subscript operator creates its own variables?

I tried to override the Subscript operator to make matrix indexing a bit more "user-friendly" in complex expressions with the following code according to the ...
5
votes
1answer
80 views

GaussianMatrix function issue

Here is my implementation of the built-in GaussianMatrix function. ...
10
votes
10answers
683 views

Matrix indexed by one number

I'm trying to find a generic way (for arbitrary dimensions) to create a matrix like so a[1] a[2] a[3] a[4] i.e where it is indexed by one number, instead of say ...
3
votes
2answers
89 views

Perform matrix/tensor contractions more efficiently

Problem: explicit index contractions for matrices using the Sum command take too long, and I want to improve the performance for complicated computations. Let me ...
1
vote
0answers
82 views

How to speed up the construction of a large matrix

As a part of a physics problem that I'm working on, I need to construct a rather large matrix. The matrix is a real symmetric $2^{m}\times 2^{m}$ matrix for some integer $m$, which we would like to ...
0
votes
1answer
86 views

problem in solving equation

this happened to me when I try to get (f) which should equal sqrt(3)/2 is there any problem in my formula or what? ...
3
votes
1answer
83 views

Plotting eigenvalues smoothly

I am trying to plot how the eigenvalues of a matrix change by changing a given a parameter t. Of course the ordering of the eigenvalues does not matter mathematically but it does when I want to make ...
1
vote
1answer
72 views

Creating a transformation matrix with respect to given bases? [closed]

Let's say I have a linear transformation $T:V\to W$, along with some bases $\{v_1,v_2\}$ and $\{w_1,w_2,w_3\}$ of each respectively. Let's say all the information I have about the transformation and ...
3
votes
3answers
144 views

How can I assign matrix values in below form? [closed]

I want to create matrix as the below fig. shows. How can I do it with a do-loop, for-loop, if-loop, or any other way? Thanks a lot...
2
votes
1answer
59 views

Efficiently Invert a Square, Block Diagonal Matrix

I am generating an n x n matrix where n is specified by DIM: ...
9
votes
0answers
158 views

Bug in PositiveDefiniteMatrixQ?

Fixed in 10.1.0. Exists in at least 9.0.1 -- 10.0.2. This seems like a bug in PositiveDefiniteMatrixQ to me: ...
3
votes
1answer
59 views

Extending matrix (x,y-axis + data) via Interpolation. Looking for elegant & efficient way to write

Please, feel free to edit the title, if necessary. Hi, this is my code working, but actually, the size of my real dataset is 100x100. So, this is very inefficient way. What would be the most ...
1
vote
1answer
79 views

Replacing negative components of a matrix with zeros [closed]

How can I replace the negative components of a matrix with zeros?
0
votes
0answers
24 views

Finding the percent difference between elements of a matrix and a list/vector [duplicate]

I have a large matrix of 24 columns, 11 rows, and a vector in the form of a one column, 11 row table. What would be the best method of finding the percent difference between each element of the matrix ...
1
vote
4answers
151 views

Non-rectangular pick of elements of a matrix

How to pick elements of a matrix that are inside a circle centered at the center of the matrix?
3
votes
1answer
153 views

How can I optimize the search between two lists, one that is changing length?

I'm trying to identify unique arrays by comparing two lists, one which is growing in length. The number of elements in the list grows as 2^n^2, where ...