The QR factorization with column pivoting does not enable us to compute
a minimum norm solution to a rank-deficient linear least squares problem,
unless 
. However,
by applying further orthogonal (or unitary) transformations
from the right to the upper trapezoidal matrix
,
using the routine xTZRQF, 
can be eliminated:
This gives the complete orthogonal factorization
from which the minimum norm solution can be obtained as
