Approximation algorithm for the Closest Vector Problem. The default implementation uses Babai's Nearest Plane Method. References:

• On Lovász' Lattice Reduction And The Nearest Lattice Point Problem, László Babai. Combinatorica 6 (1), 1-13 (1986).
• Mathematics of Public Key Cryptography, Steven Galbraith. Chapter 18 of draft 1.0