1. Replace HashMap and HashSet with std::unordered_map and
std::unordered_set respectively.
2. Extract the pair hasher into a struct pair_hash.
3. Delete collections_port.h
4. Convert explicit iterator based loops to auto based
loops where sensible.
Change-Id: Ib88bcd13a7463d18435639d3b771abaa52080efb
Since Ceres is moving to using GitHub for issues, and the Google
Code URL in the current copyright header will soon become invalid,
update all the headers.
Change-Id: I1fce70375d1bcf098591f07b4d8f01a5c1e0789c
For historical reasons we had a "using namespace std;" in port.h. This
is generally a bad idea. So removing it and along the way doing a bunch
of cpplint cleanup.
Change-Id: Ia125601a55ae62695e247fb0250df4c6f86c46c6
Rename Graph -> WeightedGraph.
Add a new Graph class, which is cheaper to construct and
work with if the weights are not needed.
This cuts down the cost of building the Hessian graph
significantly.
Change-Id: Id0cfc81dd2c0bb5ff8f63a1b55aa133c53c0c869
The schur ordering is used to construct an elimination
ordering for Schur type solvers when the user has not
supplied an elimination ordering.
The ordering algorithm does an ordered traversal of the
sparsity graph of the Hessian. The order in which this is
done used to be determined by the degree of the parameter
blocks with ties broken arbitrarily using the memory address
of the parameter blocks.
This introduced non-determinism in the solver, causing subtle
numerical differences in the value of the solution everytime
the solve was run.
This change introduces ComputeStableSchurOrdering which utilizes
a new function StableIndependentSetOrdering. The latter takes
as input an ordering of the vertices of the graph which is used
to break ties when ordering the vertice by degree. The former
constructs such an ordering by using the order in which the
parameter blocks were added to the Problem.
In this way, as long as the construction of the problem is
deterministic, the schur ordering will always be deterministic
too.
I have chosen not to delete the existing unstable implementations
of these functions as they are used by the inner iteration
minimizer.
Sometime in the near future I will clean up some of the duplicate
code and see if we can move all the code to using a stable ordering.
Change-Id: I8fbfa240d7307a2c3fe9b135f6968aa410d78780
Sameer Agarwal