Find orthogonal P and diagonal matrix D

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SUMMARY

The discussion centers on finding an orthogonal matrix P and a diagonal matrix D for the matrix A = [1 -1 0; -1 2 -1; 0 -1 1]. The eigenvalues identified are 0, 1, and 3, leading to the diagonal matrix D = [0 0 0; 0 1 0; 0 0 3]. The key point is that the columns of the orthogonal matrix P must consist of normalized eigenvectors, which ensures that P is orthogonal and simplifies the computation of the inverse, as P-1 equals P*.

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  • Understanding of eigenvalues and eigenvectors
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  • Basic linear algebra concepts
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Homework Statement



A= [1 -1 0]
[-1 2 -1]
[0 -1 1]
find orthogonal matrix P and diagonal matrix D such that P' A P = D

Homework Equations





The Attempt at a Solution


i got eigenvalues are 0, 1, 3 which make D=[0 0 0; 0 1 0; 0 0 3]
how to find P. because in my solution they mentioned about normalised eigenvectors.
 
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Find the eigenvectors. The columns of P are the eigenvectors.
 
i know after i got eigenvalues, i can find eigenvectors which is P.
my question is that in my solution, P are normalised eigenvectors. why they use normalised eigenvector instead of the eigenvector?
 
If you used unnormalized eigenvectors the diagonalization equation is P-1AP=D instead of P*AP=D. The inverse is particularly easy to find with normalized eigenvectors. If P is constructed from normalized, orthogonal eigenvectors then P will be an orthogonal matrix, making P-1=P*.
 
thanks, got it
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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