Let W be the set of all 2×2 complex Hermitian matrices, that is, the set of 2×2 complex matrices A such that Aij=Aji (the bar denoting complex conjugation). As we pointed out in Example 6 of Chapter 2, W is a vector space over the field of real numbers, under the usual operations. Verify that
(x,y,z,t)→[t+xy−izy+izt−x]
is an isomorphism of R4 onto W.