Matrix generation cleanup

1. Convert a CompressedRowSparseMatrix constructor which
takes a TripletSparseMatrix as input into a factory method
which allows the input to be transposed.

2. Move the random matrix creation routine for CompressedRowSparseMatrix
from being a standalone function to a static method.

3. Add a corresponding random matrix generation static method to
TripletSparseMatrix.

4. Add a new constructor to TripletSparseMatrix, which takes as input
the row, col and values arrays.

Change-Id: Iec7b184646818f432a5e6822bea3b2f3128a82aa

internal/ceres/schur_complement_solver.cc

@@ -547,15 +547,16 @@ SparseSchurComplementSolver::SolveReducedLinearSystemUsingEigen(
   }
 
   // This is an upper triangular matrix.
-  CompressedRowSparseMatrix crsm(*tsm);
+  scoped_ptr<CompressedRowSparseMatrix> crsm(
+      CompressedRowSparseMatrix::FromTripletSparseMatrix(*tsm));
   // Map this to a column major, lower triangular matrix.
   Eigen::MappedSparseMatrix<double, Eigen::ColMajor> eigen_lhs(
-      crsm.num_rows(),
-      crsm.num_rows(),
-      crsm.num_nonzeros(),
-      crsm.mutable_rows(),
-      crsm.mutable_cols(),
-      crsm.mutable_values());
+      crsm->num_rows(),
+      crsm->num_rows(),
+      crsm->num_nonzeros(),
+      crsm->mutable_rows(),
+      crsm->mutable_cols(),
+      crsm->mutable_values());
   event_logger.AddEvent("ToCompressedRowSparseMatrix");
 
   // Compute symbolic factorization if one does not exist.