General how to find the eigenvectors/values

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Discussion Overview

The discussion revolves around the general methods for finding eigenvalues and eigenvectors of a 3x3 matrix, including the steps involved and the mathematical principles underlying the process. The scope includes theoretical explanations and mathematical reasoning.

Discussion Character

  • Exploratory, Technical explanation, Mathematical reasoning

Main Points Raised

  • One participant inquires about the general process for finding eigenvalues and eigenvectors for a 3x3 matrix, seeking a step-by-step example.
  • Another participant suggests finding the roots of the characteristic equation and solving the linear algebra problem as a method for determining eigenvalues.
  • A different participant notes that the process for finding eigenvalues for a 3x3 matrix is similar to that for a 2x2 matrix but acknowledges that it is more complex due to the characteristic equation being a cubic polynomial.
  • One participant explains that an eigenvalue for a transformation T is defined as a number c such that Tv = cv for some non-zero vector v, leading to the conclusion that one should look for values of c that make the determinant of (T-c) equal to zero, which results in a cubic equation.
  • Another participant expresses enthusiasm about the discussion.

Areas of Agreement / Disagreement

Participants present various methods and insights regarding the determination of eigenvalues and eigenvectors, but no consensus is reached on a single approach or example. The discussion remains exploratory with multiple perspectives offered.

Contextual Notes

The discussion does not delve into specific examples or detailed calculations, and assumptions about the properties of the matrix or transformation are not fully explored.

johnnyboy2005
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this is not an assignment question...but i am just wondering in general how to find the eigenvectors/values for a 3X3 matrix...can someone show me the step by steps with an example?? don't worry, soon i will give back to this web site.:biggrin:
 
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Find the roots of the characteristic equation, solve the linear algbebra problem.
 
Pretty much the way you find eigenvalues for 2 by 2 matrices- except that it is harder! The characteristic equation is a cubic polynomial equation. Solve that for the eigenvalues.
 
an eigenvalue for T is a number c such that Tv = cv for some non zero vector v.

that means (T-c)v = 0, i.e. that T-c is singular, hence has determinant zero.

so look for those c such that det(T-c) = 0. this is a cubic equation in the coefficients of T.

I.e. if you choose a basis for the space, T becomes a matrix and you can calculate this equation and hopefully find its roots.Or you may know that T is length preserving, say it camer from geometry as a reflection or a rotation, or something like that, and then that imposes restrictions on the possible eigenvalues.
 
ah, fantastico
 

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