diff --git a/internal/ceres/covariance_impl.h b/internal/ceres/covariance_impl.h
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+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2015 Google Inc. All rights reserved.
+// http://ceres-solver.org/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+//   this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+// * Neither the name of Google Inc. nor the names of its contributors may be
+//   used to endorse or promote products derived from this software without
+//   specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: sameeragarwal@google.com (Sameer Agarwal)
+
+#ifndef CERES_INTERNAL_COVARIANCE_IMPL_H_
+#define CERES_INTERNAL_COVARIANCE_IMPL_H_
+
+#include <map>
+#include <memory>
+#include <set>
+#include <utility>
+#include <vector>
+#include "ceres/covariance.h"
+#include "ceres/problem_impl.h"
+#include "ceres/suitesparse.h"
+
+namespace ceres {
+namespace internal {
+
+class CompressedRowSparseMatrix;
+
+class CovarianceImpl {
+ public:
+  explicit CovarianceImpl(const Covariance::Options& options);
+  ~CovarianceImpl();
+
+  bool Compute(
+      const std::vector<std::pair<const double*,
+                                  const double*>>& covariance_blocks,
+      ProblemImpl* problem);
+
+  bool Compute(
+      const std::vector<const double*>& parameter_blocks,
+      ProblemImpl* problem);
+
+  bool GetCovarianceBlockInTangentOrAmbientSpace(
+      const double* parameter_block1,
+      const double* parameter_block2,
+      bool lift_covariance_to_ambient_space,
+      double* covariance_block) const;
+
+  bool GetCovarianceMatrixInTangentOrAmbientSpace(
+      const std::vector<const double*>& parameters,
+      bool lift_covariance_to_ambient_space,
+      double *covariance_matrix) const;
+
+  bool ComputeCovarianceSparsity(
+      const std::vector<std::pair<const double*,
+                                  const double*>>& covariance_blocks,
+      ProblemImpl* problem);
+
+  bool ComputeCovarianceValues();
+  bool ComputeCovarianceValuesUsingDenseSVD();
+  bool ComputeCovarianceValuesUsingSuiteSparseQR();
+  bool ComputeCovarianceValuesUsingEigenSparseQR();
+
+  const CompressedRowSparseMatrix* covariance_matrix() const {
+    return covariance_matrix_.get();
+  }
+
+ private:
+  ProblemImpl* problem_;
+  Covariance::Options options_;
+  Problem::EvaluateOptions evaluate_options_;
+  bool is_computed_;
+  bool is_valid_;
+  std::map<const double*, int> parameter_block_to_row_index_;
+  std::set<const double*> constant_parameter_blocks_;
+  std::unique_ptr<CompressedRowSparseMatrix> covariance_matrix_;
+};
+
+}  // namespace internal
+}  // namespace ceres
+
+#endif  // CERES_INTERNAL_COVARIANCE_IMPL_H_