A class which encapsulates the functionality of the QR decomposition.

Any real square matrix A (m x n) may be decomposed as A = QR where Q is an orthogonal matrix (its columns are orthogonal unit vectors meaning QTQ = I) and R is an upper triangular matrix (also called right triangular matrix).

The computation of the QR decomposition is done at construction time by Householder transformation. If a factorization is performed, the resulting Q matrix is an m x m matrix and the R matrix is an m x n matrix. If a factorization is performed, the resulting Q matrix is an m x n matrix and the R matrix is an n x n matrix.