remove the use of DCHECK_NOTNULL from numeric_diff.h Change-Id: I7fc258812b1fe4aa727eaeb9b9b834d04a631abd
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.