and can be easily computed for any trial value of from (23) and (24), and it is only twice that the linear system (9) is solved for and 1. Also, it only takes a few vector operations to evaluate the step length and according to (12) and (13). Thus, can be cheaply computed and applied to a one-dimensional search scheme.
and 
can be easily computed 
from (23) and (24), and it is only twice that the linear system (9) 
and 1. Also, it only takes a few vector operations 
and 
according to (12) and (13). Thus, 
can be cheaply computed and applied to a one-dimensional search scheme.