RTZ ALGORITHM: Outline
Repeat until A is reduced to a Real Schur Form:
- Step 1: Choose a pair (k, m)
- Step 2: Use orthogonal transformations to reduce 3x3 matrices A[k,m,m+1] and A[k+1,m,m+1] to Real Schur Forms
2x2 blocks on the diagonal define a pair of real or complex eigenvalues of A
Product of the orthogonal transformations gives the Real Schur vectors