Use absl hash containers for graph algorithms
This reduces pre-processor time when finding an
ordering automatically substantially.
Before:
ComputeStableSchurOrdering
Delta Cumulative
CreateHessianGraph : 0.50324 0.50324
Preordering : 0.00692 0.51017
StableIndependentSet : 0.26341 0.77358
ConstantParameterBlocks : 0.00095 0.77453
Total : 0.23978 1.01431
After:
ComputeStableSchurOrdering
Delta Cumulative
CreateHessianGraph : 0.17183 0.17183
Preordering : 0.00226 0.17409
StableIndependentSet : 0.12510 0.29919
ConstantParameterBlocks : 0.00073 0.29991
Total : 0.01638 0.31629
Change-Id: I50bbac69f8b3f19240a61a218913cebf34da0db5
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.