tree ddb1436da6ee053cd63cb1ecd7b1c2af32f1e7a6
parent 6a2bcaa1d55d38bc10d043f1458657caac2be7a7
author Sameer Agarwal <sameeragarwal@google.com> 1382565067 -0700
committer Keir Mierle <mierle@gmail.com> 1382643638 +0000

Add BlockRandomAccessDiagonalMatrix.

This class is used in the SchurJacobiPreconditioner for
storing the preconditioner matrix. Using it speeds up
the computation of the preconditioner by ~15% due to
the elimination of a hash table lookup.

Change-Id: Iba2b34aad0d9eb9bcb7f6e6fad16aa416aac0d2a