Let V be the vector space of all 2 x 2 matrices with real coefficients.
Let T be the linear transformation T: V → V defined by T(A) = A^T (the transpose of the matrix A).
For example, if A = [1 2; 1 3], then TA = [1 1; 2 3].
Using the standard basis e1 = [1 0; 0 0], e2 = [0 1; 0 0], e3 = [0 0; 1 0], and e4 = [0 0; 0 1], the matrix Mt which describes the linear transformation T in this basis is given by: