tree 4a1bbd11ff6516e30a060e91e21e2e5e4aea81f6
parent ff8a13d4a52a70818c4f7951a8dbf099cccc546e
author Sameer Agarwal <sameeragarwal@google.com> 1519091220 -0800
committer Sameer Agarwal <sameeragarwal@google.com> 1519250325 -0800

An implementation of SubsetPreconditioner.

The key idea being, use some subset of the rows of the Jacobian
as the preconditioner.

This CL only implements the preconditioner assuming that the row
selection has already been done. How the rows are selected will be
left to the user based on their knowledge of the problem.

A follow up CL will hook this preconditioner into the rest of the
solver.

Change-Id: I3e18dc57811116534e9ddf35d7b154bcce496d3b