# Questions tagged [eigenvalues]

Questions on symbolically or numerically determining the eigenvalues of matrices (Eigenvalues, Eigensystem) or differential equations (DEigenvalues, DEigensystem, NDEigenvalues, NDEigensystem) in Mathematica. Also includes determining the eigenvalues of differential equations with DSolve or NDSolve.

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### When solving eigenvalues, what does the factor in front of the Root[] mean?

I tried to solve the eigenvalue of a matrix like this: ...
1 vote
21 views

### Characteristic equation and eigensystem yield different results [closed]

I am comparing the eigenvalues one obtains with Eigensystem of a matrix $\Omega$ and by solving the characteristic equation for the same matrix, but when I do so I get different results: what am I not ...
• 11
119 views

### Fitting Eigenvalues of a 8*8 matrix to experimental data

I have an 8x8 matrix which contains some parameters with a certain range. I am trying to fit the eigenvalues of this matrix to my experimental data with the goal of having the best fit extracting the ...
• 41
1 vote
96 views

1 vote
38 views

### Using DEigensystem with parametrized cuboid

The following code where Cuboid has a predefined dimensions {1, 1, 1} works fine: ...
• 2,202
116 views

### NDEigensystem does not work when using nonlinear operator [closed]

I am trying to find the eigenvalues of the stationary Gross Pitaevskii equation using the NDEigensystem command via ...
84 views

### Break symbolic eigenvalue calculation early

I am computing eigenvalues of matrices with single monomial entries (x,y,z, etc.) and for efficiency, need to truncate calculations early if any eigenvalues contain non-linear (x^{2}, \sqrt(x),x*y etc....
162 views

### Dirac equation for a Coulomb potential in 2D with NDEigensystem

I want to numerically solve the ground state wave function of the hydrogen atom with the Coulomb potential using the NDEigensystem. Here is the code to get the ground state wave function from the ...
• 51
223 views

### Numerical ground state wavefunction of Schrödinger equation with a Coulomb potential in 2D from NDEigensystem

I want to numerically solve the ground state wave function of the hydrogen atom with the Coulomb potential using the NDEigensystem. Here is the code to get the ground state wave function from the ...
• 51
1 vote
92 views

### Problem to solve computationaly and plot the phase portrait of a nonlinear ode system

I am here again to see if some one can help me. This time, I have problem to solve, computationally and plot the phase portrait of a nonlinear ode system (The Duffing Equation with just the spring ...
96 views

### Eigenvalue Problem - Nullspace Basis

I need to solve an eigenvalue problem where some of the eigenvalues are 0. Due to the fact that I just need the eigenvectors associated to the 0-eigenvalues in some cases I'd just like to calculate ...
• 134
1 vote
124 views

### Using Mathematica to find the eigenvectors

I would like some clarification about solving for eigenvectors in Mathematica. I am looking at the following matrix: \begin{equation*} L = \begin{pmatrix} 0 & m(1+\frac{kmwr}{\lambda}) \\ q(1-kpx)...
• 179
37 views

### Root function in the output [duplicate]

I was calculating the eigenvalues of a matrix and the output contained some eigenvalues like: ...
• 21
1 vote
133 views

• 103
1 vote
43 views

### Wrong eigenvalues for 2D QHO using DEigensystem[]

I try to solve 2D Quantum Harmonic Oscillator using DEigensystem[] in Mathematica 13.0. Here is my code: ...
• 11
1 vote
98 views

### Issue with numerical evaluation of eigensystem

I am calculating eigenvalues of a Hamiltonian numerically but I am getting avoided crossings and gap in the curves (see the output of the code) which are not correct. Please help me out to resolve ...
• 71
93 views

### How should a function written through the Module be written in the FindMinimum correctly?

There is a function that is written using a module ...
• 1,883
1 vote