Simplify, cleanup and instrument SchurComplementSolver.
The instrumentation revealed that EIGEN_SPARSE can be upto
an order of magnitude slower than CX_SPARSE on some bundle
adjustment problems.
The problem comes down to the quality of AMD ordering that
CXSparse/Eigen implements. It does particularly badly
on the Schur complement. In the CXSparse implementation
we got around this by considering the block sparsity structure
and computing the AMD ordering on it and lifting it to the
full matrix.
This is currently not possible with the release version of
Eigen, as the support for using preordered/natural orderings
is in the master branch but has not been released yet.
Change-Id: I25588d3e723e50606f327db5759f174f58439e29
2 files changed
