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
diff --git a/internal/ceres/block_random_access_sparse_matrix.h b/internal/ceres/block_random_access_sparse_matrix.h
index a6b5f39..27b1029 100644
--- a/internal/ceres/block_random_access_sparse_matrix.h
+++ b/internal/ceres/block_random_access_sparse_matrix.h
@@ -47,7 +47,7 @@
namespace ceres {
namespace internal {
-// A threaf safe square block sparse implementation of
+// A thread safe square block sparse implementation of
// BlockRandomAccessMatrix. Internally a TripletSparseMatrix is used
// for doing the actual storage. This class augments this matrix with
// an unordered_map that allows random read/write access.
