Proving Trace Independence in Linear Algebra Homework

Click For Summary
The discussion focuses on proving that the trace of a matrix is independent of the chosen orthonormal basis. It begins with the definition of trace as the sum of the inner products involving the matrix and basis vectors. Participants note that trace relates to eigenvalues, which remain constant across different bases. The challenge lies in expressing the relationship between a matrix and its representation in another basis to demonstrate this independence. Ultimately, the conversation emphasizes the need to connect these concepts to solidify the proof of basis independence for the trace.
zheng89120
Messages
139
Reaction score
0

Homework Statement



let:
Trace(A) = Ʃ(i=1..n) (ei|A|ei)

Show that trace is independent of the orthonormal basis chosen.

Homework Equations



linear algebra

The Attempt at a Solution



trace is related to the eigenvalues, which are constant?
 
Physics news on Phys.org
zheng89120 said:

Homework Statement



let:
Trace(A) = Ʃ(i=1..n) (ei|A|ei)

Show that trace is independent of the orthonormal basis chosen.

Homework Equations



linear algebra

The Attempt at a Solution



trace is related to the eigenvalues, which are constant?

IF A a diagonalizable and IF the ei happen to be eigenvectors, then sure, it's easy to see the trace is the sum of the eigenvalues. But how does that help you show it's basis independent? How do you write the relation between A and A written in a different basis?
 
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?

Similar threads

  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 30 ·
2
Replies
30
Views
1K
  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K