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Matrices satisfying certain relations

by neginf
Tags: matrices, relations, satisfying
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Nov21-12, 09:15 AM
P: 56
How do you find matrices a,b,c satisfying
c=a*b*a^-1 ?
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Nov21-12, 09:37 AM
P: 15
If you know what's diagonalization, you can skip this.

For a to be diagonalizable, A=PDP^-1, where

P is an invertible matrix whose columns are A's eigenvector (order of these columns doesn't matter). C is a diagonal matrix that has all A's eigenvalues

So for a 3x3 diagonalizable matrix
λ1 0 0
0 λ2 0
0 0 λ3

λ{1,2,3} are A's eigenvalues

[v1 v2 v3]
v{1,2,3} are A's eigenvectors

From those 3 equations in your post you can see that a, b and c have to be all diagonal matrices.

Also, a has to have b's eigenvalues, b has to have c's eigenvalues and c has to have a's eigenvalues. And of course, a has to have c's eigenvectors... etc

Not sure how i would start solving this, but I hope this helps.
Nov22-12, 03:33 AM
P: 144
Quote Quote by aija View Post
From those 3 equations in your post you can see that a, b and c have to be all diagonal matrices.
Hi Aija, your statement above is just wrong. From those 3 equations, you should immeditately observe the solution a=b=c=M, where M is any invertible matrix, and the "problem" is to determine the remaining solutions, if any.

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