1. Remove constant_sparsity from LinearSolver::Options. It introduces
unnecessarily complexity in the structure of linear solvers and preconditioners.
This is the first step towards cleaning up the Preconditioner interface.
2. Minor tweaks and cleanups to the various linear solvers.
diff --git a/internal/ceres/compressed_row_sparse_matrix.cc b/internal/ceres/compressed_row_sparse_matrix.cc
index 95edf53..e006e10 100644
--- a/internal/ceres/compressed_row_sparse_matrix.cc
+++ b/internal/ceres/compressed_row_sparse_matrix.cc
@@ -40,7 +40,13 @@
namespace {
// Helper functor used by the constructor for reordering the contents
-// of a TripletSparseMatrix.
+// of a TripletSparseMatrix. This comparator assumes thay there are no
+// duplicates in the pair of arrays rows and cols, i.e., there is no
+// indices i and j (not equal to each other) s.t.
+//
+// rows[i] == rows[j] && cols[i] == cols[j]
+//
+// If this is the case, this functor will not be a StrictWeakOrdering.
struct RowColLessThan {
RowColLessThan(const int* rows, const int* cols)
: rows(rows), cols(cols) {
