diff --git a/internal/ceres/lapack.h b/internal/ceres/lapack.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_LAPACK_H_
+#define CERES_INTERNAL_LAPACK_H_
+
+#include <string>
+#include "ceres/internal/port.h"
+#include "ceres/linear_solver.h"
+
+namespace ceres {
+namespace internal {
+
+class LAPACK {
+ public:
+  // Solve
+  //
+  //  lhs * solution = rhs
+  //
+  // using a Cholesky factorization. Here
+  // lhs is a symmetric positive definite matrix. It is assumed to be
+  // column major and only the lower triangular part of the matrix is
+  // referenced.
+  //
+  // This function uses the LAPACK dpotrf and dpotrs routines.
+  //
+  // The return value and the message string together describe whether
+  // the solver terminated successfully or not and if so, what was the
+  // reason for failure.
+  static LinearSolverTerminationType SolveInPlaceUsingCholesky(
+      int num_rows,
+      const double* lhs,
+      double* rhs_and_solution,
+      std::string* message);
+
+  // The SolveUsingQR function requires a buffer for its temporary
+  // computation. This function given the size of the lhs matrix will
+  // return the size of the buffer needed.
+  static int EstimateWorkSizeForQR(int num_rows, int num_cols);
+
+  // Solve
+  //
+  //  lhs * solution = rhs
+  //
+  // using a dense QR factorization. lhs is an arbitrary (possibly
+  // rectangular) matrix with full column rank.
+  //
+  // work is an array of size work_size that this routine uses for its
+  // temporary storage. The optimal size of this array can be obtained
+  // by calling EstimateWorkSizeForQR.
+  //
+  // When calling, rhs_and_solution contains the rhs, and upon return
+  // the first num_col entries are the solution.
+  //
+  // This function uses the LAPACK dgels routine.
+  //
+  // The return value and the message string together describe whether
+  // the solver terminated successfully or not and if so, what was the
+  // reason for failure.
+  static LinearSolverTerminationType SolveInPlaceUsingQR(
+      int num_rows,
+      int num_cols,
+      const double* lhs,
+      int work_size,
+      double* work,
+      double* rhs_and_solution,
+      std::string* message);
+};
+
+}  // namespace internal
+}  // namespace ceres
+
+#endif  // CERES_INTERNAL_LAPACK_H_