Drop use of POSIX M_PI_2 and M_PI_4 Change-Id: I310fcf3c3c369d46b2c7b1be0831e48eb559fb9d
Ceres Solver is an open source C++ library for modeling and solving large, complicated optimization problems. It is a feature rich, mature and performant library which has been used in production at Google since 2010. Ceres Solver can solve two kinds of problems.
Please see ceres-solver.org for more information.