Questions on the manipulation of matrices in Mathematica.

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1answer
164 views

An issue regarding Eigenvalues function [closed]

Can anybody please kindly explain to me why the members of the output vector produced by the following example are not equal to zero? ...
1
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1answer
2k views

Importing a matrix from a text file

I have a $4 \times N$ matrix in a .txt file of the form: -17.071 137.567 16.554 0.65 -16.873 136.138 16.934 0.7 -15.397 135.738 16.894 0.7 -14.7 135.982 15.9 0.6 ...
1
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3answers
2k views

How do I create a matrix of functions?

I'm trying to create a matrix in which the elements are functions of two variables, but I can't figure out how to do it. Is it possible? The only way I could figure out is to define the matrix in ...
2
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1answer
481 views

Solving an equation involving a determinant

I have a matrix which doesn't include numerical values. There are four variables in it. It is defined by ...
3
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2answers
845 views

All possible solutions to the Matrix Equation (free variables appearing)

I am attempting to solve a system of linear equations using LinearSolve[] . In my case, the number of unknowns are more than constraints. I learnt that LinearSolve ...
10
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3answers
422 views

Permanent minors

The function Minors yields the minors of a matrix. Is there a function that yields the permanent minors of a matrix?
12
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1answer
2k views

Eigenvalues and Determinant of a large matrix

Can anybody kindly explain to me what is going wrong regarding a simple problem I have? I can find the eigenvalues of a large matrix using Eigenvalues[], but when I ...
1
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1answer
80 views

Confirming the existence of a function related to a matrix

Is it possible to get an answer to the following question in Mathematica? Let $M$ be a $n$ by $n$ matrix, is there a function $m:\mathbb{N}\times \mathbb{N}\rightarrow \mathbb{Z}$ such that ...
7
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1answer
608 views

TensorContract of inverse matrix

Matrix inverse in mathematica If $A$ is an invertible $n \times n$ matrix, then $A\cdot A^{-1} = I$. To get this statement in Mathematica, you need the assumption ...
11
votes
2answers
3k views

How to use “Drop” function to drop matrix' rows and columns in an arbitrary way?

The built-in function "Drop" can delete a Matrix's row and column. Typical syntax for "Drop" is as follows: Drop[list,seq1,seq2...] But what if I want to drop a ...
4
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0answers
162 views

How to accelerate updating some parts of sparse matrices?

I am trying to update some parts of an specific matrix as rapidly as possible. In what follows, I first set up the basics things that I want to use ...
6
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1answer
169 views

How to calculate only four elements per column in a block matrix?

I have a matrix generated like this : Table[Sequence @@ {f[t[[i]], j, x], g[t[[i]], j, x]}, {i, 16}, {j, 3}] where $f$ and $g$ are two different functions, $t$ ...
8
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3answers
690 views

Multiply a list of matrices by a list of vectors

How does one multiply a list of matrices by a list of vectors, elementwise? For example, multiplying ...
0
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1answer
519 views

How Simplify and Assume can be combined on matrix products?

What I am trying to do is to simplify some expressions involving matrices! The problem is that Simplify[] considers the simplifications based on alphabetical order and everything is Commutative. For ...
8
votes
1answer
276 views

inverse of abstract matrix

If you assume the matrix $A$ is invertible, then $A^{-1} \cdot A = I$. Is there an assumption for invertibility in Mathematica 9? How can one make the following evaluate to the identity matrix $I_3$? ...
10
votes
2answers
414 views

Speed up 4D matrix/array generation

I have to fill a 4D array, whose entries are $\mathrm{sinc}\left[j(a-b)^2+j(c-d)^2-\phi\right]$ for a fixed value of $\phi$ (normally -15) and a fixed value of $j$ (normally about 0.00005). The way ...
25
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2answers
5k views

How to form a block-diagonal Matrix from a list of matrices?

For example, like this: I know join[...] works, but it is a bit troublesome for multiple matrices. I also tried DiagonalMatrix[...], but DiagonalMatrix can only form a matrix from a list of ...
3
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3answers
263 views

How to transform and swap columns of this matrix in a simple way? Version 2

So, earlier today I asked the question How to transform this matrix & swap its columns in a simple way? and was given useful and elaborated answers. Now, I'm still not used to the "Array", ...
0
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2answers
1k views

How to get complement from two matrices?

This is a special case of my question How to do nor on matrices? ...
3
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4answers
432 views

How to transform this matrix & swap its columns in a simple way?

I would like to transform matrix $\mathbf A = \begin{pmatrix} a&b&i&j\\ c&d&k&l \\ e&f&m&n \\ g&h&o&p \end{pmatrix}$ into matrix $\mathbf B = ...
0
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1answer
165 views

How to do nor on matrices?

Supose I have matrices a b and c like a = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; b = {7, 8, 9}; c = {{1},{4},{7}}; I want to get ...
12
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2answers
3k views

Badly conditioned matrix (General::luc)

With some matrices, I am receiving the following message: ...
9
votes
1answer
9k views

Quick Hessian matrix and gradient calculation?

I am absolutely new to Mathematica and I actually want to try implementing a little optimization method . Long story short assuming I have a predefined two-variable function f(x,y) I want to ...
2
votes
1answer
267 views

Can I reduce a matrix inequality such as $\mathbf x^\prime\mathbf A\mathbf x > \mathbf x^\prime\mathbf x$?

I'm new to Mathematica. When I do linear algebra, I wonder if I can have an inequality such as $\mathbf x^\prime\mathbf A\mathbf x > \mathbf x^\prime\mathbf x$, where $\mathbf x$ is a column vector ...
0
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1answer
178 views

Discrete 3D plots of median ratios of two 2D matrices of lists of values

Lets say I have 2 2D arrays where each cell contains a list of values: Example: ...
0
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0answers
48 views

Inverting a matrix [duplicate]

Possible Duplicate: Why does MatrixForm affect calculations? I am facing a strange behaviour from Mathematica when asking it to invert the following matrix: ...
3
votes
1answer
317 views

Efficiently finding the maximum value of a column in a matrix

Imagine I have a matrix of the following form: TestArray = $((a_1,b_1,...),(a_2,b_2,...),(a_3,b_3,...),...)$, where a specific example might be: TestArray = ...
1
vote
3answers
682 views

More than one expression in the Table[] command?

I would like to construct a Matrix using the Table[] command. The issue is that I would like to use more than one expression for it. What I need to obtain is something like this : ...
5
votes
1answer
314 views

How to define and compute various properties of a variable size matrix

I have a rather simple question, but I have not been able to figure out how to implement a solution in Mathematica. I would like to define a variable size square matrix, say an N x N matrix A, whose ...
2
votes
2answers
234 views

How can I shift the frame ticks to the corner of each element-cell in a Matrixplot?

I am using the following code,to create a Legend for my plot. I would like to shift (or re-position) the frameticks to the corner of each of the cell-elements instead of being in their middle. I ...
0
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0answers
75 views

Trying to access element of a matrix [duplicate]

Possible Duplicate: Question about MapThread and Dynamic I'm trying to extract element of a matrix. Let's suppose that the matrix is ...
3
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2answers
373 views

Dynamic matrix multiplication

I have the following problem: I want to multiply two matrices and sum them to another matrix C. A.B+ 2B Easy! The matrix A varies as a function of three inputs a,b and c. The second matrix, B, is a ...
16
votes
3answers
521 views

Compiling LinearSolve[] or creating a compilable procedural version of it

Earlier today I had a discussion with a representative at Premier Support about the 2 questions I've asked here over the past couple of days: Seeking strategies to deploy a function securely ...
9
votes
2answers
284 views

Correct way to generate large data sets (i.e.forward yield curve )

I would like to generate a set of forward yield curve matrix of size 1000 x 100. First I defined my SparseArray of 1000 x100: ...
1
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1answer
114 views

How can I find the row differences of a matrix?

How can I compute the row differences of an m x n matrix to obtain an m-1 x n matrix; that is, given how do I obtain
0
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3answers
639 views

How can I fill in a matrix at every iteration of a Do loop?

I have a matrix whose dimensions are 26x26x3. For my assignment I have written a program which is using a Do loop (maxx=maxy=10,maxz=2): ...
3
votes
3answers
357 views

Correct way to populate a DiagonalMatrix?

I would like to create a series of correlation matrices that starts with : sensMat[[1]] = DiagonalMatrix[ { 1,1,1,1,1 } ]) // MatrixForm and iterates in 0.1 ...
5
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1answer
2k views

Problem with plotting eigenvalues

I want to plot the eigenvalues of a matrix which is dependant on a parameter (well, actually I want to plot a tight-binding electronic band structure). The dimension of the hamitonian matrix is ...
1
vote
3answers
1k views

How do I combine the data from two tables according to a rule of my own devising?

I have two matrices a = m x 5 and b =m x 5 (m is large, say 1,000) which are already sorted as below: How to generate a new matrix c = m x 5 which consists: Column 1: exact replica of Column 1 ...
-1
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2answers
629 views

Correct way to compare arrays and do conditional evaluations

I would like to compare two arrays a=: and b= and get: using: (b/.(b_?Positive->a+b))//MatrixForm but this doesn't seem to work? Can ...
2
votes
3answers
3k views

Correct way to remove matrix columns?

I start off with m = 1000 x 5 matrix, and I would like to remove first column to get 1000 x 4 matrix and repeat again for ...
-2
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1answer
122 views

Can Depth be used as an equivalent for MatrixQ?

Given an expression x, are the following two statements interchangable with no exceptions? Depth[x] - 1 == 2 ...
0
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1answer
753 views

How to efficiently fill in matrix values?

I would like to efficiently fill in or assign values to matrix m: m={ {a[1,1],a[1,2],a[1,3],a[1,4]}, {a[2,1],a[2,2],a[2,3],a[2,4]}, {a[3,1],a[3,2],a[3,3],a[3,4]}, ...
2
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3answers
232 views

MatrixForm explanation as why row extract is displayed as a column?

I have a 5 x 5 matrix: cdsSpread5yrs = But after doing a row extract, why is it displaying as a column? ...
2
votes
1answer
545 views

RowReduce: Solving for the resource vector (a, b, c) in Augmented Matrix

Here are two examples: RowReduce[{{3, 1, a}, {2, 1, b}}] evaluates to {{1, 0, a - b}, {0, 1, -2 a + 3 b}} but ...
0
votes
2answers
495 views

Matrix Plot – Little Exercise

Hi there, mathematicians. I'm not very good at coding plots in Mathematica, so I was hoping that one of you could help me solve a problem I'm having. I have the following matrix plot: ...
9
votes
2answers
1k views

How to transform a 3D image by an affine transformation matrix

I have a question concerning Image Processing: I have a stack of images, which I can compose to a 3D image using Image3D. Additionally I have a 4x4 affine transformation matrix. I would like to ...
4
votes
2answers
417 views

Rearranging a matrix

I would like to convert a matrix which has a structure like this: {{"A", 10, "D", 1},{"B", 3, "A", 2},{"C", 7, "B", 3},{"D", 6, "C", 4}}//MatrixForm//Print; ...
9
votes
1answer
360 views

Verifying and deriving basic (block) matrix identities

How can I use the new symbolic matrix/tensor capabilities to verify matrix identities, such as (1) or (2) Even better, how can I ask Mathematica to derive expressions for X, Y, Z, and U like ...
3
votes
3answers
241 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 ...