Matrix ( 4x4) & Determinant
Trace of a Matrix:Σ_{i=1 to n} a_{ii } Properties: tr (A+B) = tr(A) + tr(B)(1) ; tr(cA) =c*tr(A) (2) where c is a scalar ; tr(AB) =tr(BA)......(3) tr(A) =tr(A^{T})(4) which means that trace of a matrix and that of its transpose are identical. 
Trace of a product of matrices: it behaves similarly to a dot
product of vectors.
Trace is invariant under cyclic permutations : tr(ABCD) = tr(BCDA)=tr(CDAB)=tr(DABC); This is known as cyclic property. But arbitrary permutations are not allowed.In general, tr(ABCD) != tr(ACBD); However, if 3 symmetric matrices are concerned, any permutation is allowed. For more than 3 factors, this is not true. Trace is similarity invariant, i.e. if P^{1}AP=A, tr(P^{1}AP)=tr(A). If A is symmetric and B is antisymmetric, tr(AB)=0; 
The trace corresponds to the derivative of the determinant. Suppose
where θ is the angle of rotation of the coordinate axis. These are one parameter family of linear transformations having determinant 1, so they preserve area. The derivative of this family at θ =0 , the identity rotation is antisymmetric matrixa de having trace zero. Trace is a linear operator and hence commutes with its derivative. d tr(A)=tr(dA); Unlike the determinant, the trace of the product is not the product of traces. What is true is that the trace of the tensor product of two matrices is the product of their traces:

The trace of a 2by2 complex matrix is used to classify Möbius transformations. First the matrix is normalized to make its determinant equal to one. Then, if the square of the trace is 4, the corresponding transformation is parabolic. If the square is in the interval [0,4), it is elliptic. Finally, if the square is greater than 4, the transformation is loxodromic. See classification of Möbius transformations. 
link:1, 
Matrix Norms : link 1norm is the maximum of the absolute sum of respective columns, infinitynorm is the maximum of the absolute sum of the respective rows, euclidean norm is the square root of the sum of the square of all the matrix elements. 