# Orthogonal transformation

1. Homework Statement
My statistical mechanics book says that if M is an real, symmetric n by n matrix, and U is the matrix of its eigenvectors as column vectors, then the transformation UMU^{-1} preserves the trace of M. Is that true? If so, is it obvious? If it is true but not obvious, how do you prove it?

2. Homework Equations

3. The Attempt at a Solution

## Answers and Replies

Related Calculus and Beyond Homework Help News on Phys.org
Dick