Borrar filtros
Borrar filtros

how to find eigenvalues using the determinant ?

48 visualizaciones (últimos 30 días)
aiman el 13 de Nov. de 2022
Respondida: Christine Tobler el 14 de Nov. de 2022
I have mass and stiffness matrices and i want to find the eigenfrequency using det(K-w^2*M)=0 while K and M are the matrices and w is the eigenvfrequencies.How can i change this equation into mode and getting w ?

Respuesta aceptada

Christine Tobler
Christine Tobler el 14 de Nov. de 2022
The determinant should only be used explicitly to solve an eigenvalue problem for symbolic calculation (for example, when you solve a 2-by-2 problem by hand). In numeric computations, the determinant is not robust and not advised to use.
You can compute the eigenvalues and eigenvectors using the EIG function, [V, D] = eig(K, M). This gives you eigenvalues (diagonal of D) and eigenvectors (columns of V) of this problem. The matrices satisfy
norm(K*V-M*V*D) % == 0 up to round-off error
To get the w value you want, you simply take the square root of the eigenvalues, sqrt(diag(D)).

Más respuestas (1)

John D'Errico
John D'Errico el 13 de Nov. de 2022
Editada: John D'Errico el 13 de Nov. de 2022
This is a generalized eigenvalue problem. READ THE HELP FOR EIG. If you pass in both matrices, it still computes the eigenvalues.
Do you want to use the determinant? NO! Learn to use eig.


Más información sobre Eigenvalues & Eigenvectors en Help Center y File Exchange.


Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by