Arrangement of eigenvalues in a Diagonal matrix

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coconut62
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Homework Statement



Is it necessary to arrange the eigenvalues in increasing value order?

As shown in the image attached, if I arrange my eigenvalues -2, -1, 1 diagonally, my D would be
2^8 , 1, 1 diagonally.

However if i arrange it as, say, -1, 1, -2, my D would be different.

Just want to make sure of it, thanks.
 
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  • Handwritten worked solution of Example 7C.2.3 on a printed page: eigenvalues of a 3x3 matrix found from det(A - λI) = 0, eigenvectors for λ = -1, 1, -2, the matrix P, the diagonal matrix D, and D^8 written out.
    1497694_10151999292832830_762180400_n.jpg
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coconut62 said:

Homework Statement



Is it necessary to arrange the eigenvalues in increasing value order?

As shown in the image attached, if I arrange my eigenvalues -2, -1, 1 diagonally, my D would be
2^8 , 1, 1 diagonally.

However if i arrange it as, say, -1, 1, -2, my D would be different.

Just want to make sure of it, thanks.

Good work. Yes, there is more than one matrix P that will diagonalize A. You can arrange the eigenvectors in P in a different order and get the eigenvalues in a different order along the diagonal. I don't think anyone order is more correct than another.