# Trace of Matrix

The sum of the elements of a square matrix A lying along the principal diagonal is called the trace of A, i.e., tr(A)

Thus if A = [aij]n Ã— n , then

tr(A) =

# Properties of trace of a matrix

Let A = [aij]n Ã— n and B = [bij]n Ã— n and Î» be a scalar, then
• tr(Î»A) = Î»tr(A)
• tr(A + B) = tr(A) + tr(B)
• tr(AB) = tr(BA)