Matrix

Trace of Matrix

The trace of a square matrix is the sum of its diagonal entries. $tr(A)=a_{11}+\cdots +a_{nn}$

According to DL book,, the trace operator is useful to represent operations without summation notation.

For example, the trace operator provides an alternative way of writing the Frobenius Norm of a matrix: $\Vert A{\Vert }_F=\sqrt{Tr(A{A}^T)}$