# Tagged Questions

Questions on the manipulation of matrices in Mathematica.

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### How to do abstract matrix operation?

In this simple example, I have 2 lists, each of which contains 3 matrices。 $J$ here is also a matrix with the same dimension. What I want is $aJc+bJ(b+c)$, but if I use dot product, the result is as ...
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### How to remove parts of an expression [on hold]

I have an expression where terms Transpose[R].R appear. R is a matrix with the property Transpose[R].R=IdentityMatrix[3]. How ...
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### Python Convolve2D functionality in Mathematica

I am new to mathematica. I am looking for an alternative for scipy.signal.convolve2d. I did find functions like ListConvolve, ...
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### Expectation of summation with symbolic indices

I am working on symbolic computations with mathematica. I faced an issue with taking expectation of a large expression involving summations with symbolic indices. Is it possible to take expectation ...
5k views

### Fastest way to calculate matrix of pairwise distances

It is a very common problem that given a distance function $d(p_1,p_2)$ and a set of points pts, we need to construct a matrix ...
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### Eigenenergies of a symmetric tridiagonal matrix [on hold]

we consider the time independent Schrodinger equation (TISH) where we want to calculate the first few instantaneous eigenergies. Discretizing space we get : So we can rewrite the TISH as, (where ...
299 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 ...
329 views

### How to remove a line of a matrix if not all elements are numeric?

I have a matrix a n columns and m lines. I'd like to efficiently remove the lines that are not entirely composed of numeric ...
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### The new introduced EulerMatrix problem

In the present version of Mathematica, there is a new command EulerMatrix[{α, β, γ}])// MatrixForm I read its document and I still don't understand it. For me, ...
261 views

### Generic Matrices

A multivariate Gaussian distribution for $k$ dimensions looks like this: $$\frac{1}{\sqrt{(2\pi)^k|\mathbf \Sigma|}}\mathbf e^{ -\frac 1 2 \mathbf x^T \mathbf \Sigma^{-1}\mathbf x }$$ $\mathbf x$ ...
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### Algorithm to generate a certain matrix

I am looking for a convenient way to generate a matrix of the following symmetric form (numbers could also run from -3 to +3 or just from -1 to +1): Tips, anybody?
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### Transform an expression into a function [on hold]

I have a matrix of the form Mat = {{2a, 7a},{5a, 3a},{a, 2a}} (the actual matrix is a hugely complicated one of size 64x64, but the idea is exactly the same). I ...
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### How to make the conjugate transpose

I have a problem to make the conjugate and transpose the matrix.May anyone help me please. ...
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### How to generate a Markov Matrix efficiently

A Markov Matrix is a square matrix,which have two features: All elements great than or equal to $0$(But I hope all element great than or equal to $0.1$) All the columns add up to $1$ I have a ...
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### Remove columns basing on binary sequence

Possibly it is duplicate, still I could not find here elegant way to remove matrix columns basing on binary sequence. i.e. if I apply {1,1,0,0,1,0,1} to matrix it should delete columns 3,4 and 6.
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### Aguilera-Perez Algorithm of $nD$ rotation matrix [on hold]

I want to compute a general $nD$ rotation matrix which corresponds to a rotation by an angle $\theta$ around an $(n−2)$-dimensional subspace. I found the Aguilera-Perez algorithm in their paper: ...
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### Expanding a matrix in a set of matrices

Consider a vector $a=\{a1,a2,a3\}$. I computed $e^{i a\cdot \sigma}\qquad \sigma: {\rm Pauli\ matrices}$ and then applied the command ExpToTrig. Now I want to expand the above result in terms of ...
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### Probems using 2 For and a AppendTo to cycle through my Equation to solve some matrixes

I am trying to solve a few problems here. I have an equation with multiple variables that I am trying to solve in For loop method. I will attach the file below. In addition I am trying to get it to ...
103 views

### how to update elements in a matrix with position identified in a list

I am new to mathematica. Could you pls help me on how to write this: I have a $5\times 10$ matrix, for example, ap = ConstantArray[0.001, {5, 10}] I have the ...
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### How can we assign value given by Eigenvalue command to variables? [closed]

I want to assign value of eigen value given by eigenvalue command in mathematica to variables so I can use further in programme.
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### Kronecker product

I have a problem, I want to compute kronecker product as given below; ...
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### How to automate a computation and save the outputs?

I'm working with neutrino oscillations in matter and i'm computing the oscillation probabilities as functions of the Energy. This is what i have ...
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### Dynamic input for Complex, Determinant output problems [duplicate]

I'm having trouble using Complex with Dynamic real and imaginary inputs. The inputs come from a matrix of popup menus: ...
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### Group matrix values by column [closed]

Original Question: I have a list {{a, 1}, {b, 3}, {c, 1}, {d, 2}, {e, 3}}. I want to be able to group the the first number in each pair that has the same second ...
62 views

### Plotting Matrix versus Matrix [closed]

So I recently started using Mathematica and I haven't been able to figure out how to simply plot elements of one matrix versus another matrix which are not directly related or are not a function of ...
393 views

### Nonlinear matrix equation solving in Mathematica

is it possible to solve below equation in Mathematica? A.X+B.Exp[X]==C A, B are square ...
60 views