diff --git a/internal/ceres/lapack.cc b/internal/ceres/lapack.cc
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+++ b/internal/ceres/lapack.cc
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+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2013 Google Inc. All rights reserved.
+// http://code.google.com/p/ceres-solver/
+//
+// 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)
+
+#include "ceres/lapack.h"
+#include "glog/logging.h"
+
+// C interface to the LAPACK Cholesky factorization and triangular solve.
+extern "C" void dpotrf_(char* uplo,
+                       int* n,
+                       double* a,
+                       int* lda,
+                       int* info);
+
+extern "C" void dpotrs_(char* uplo,
+                        int* n,
+                        int* nrhs,
+                        double* a,
+                        int* lda,
+                        double* b,
+                        int* ldb,
+                        int* info);
+
+extern "C" void dgels_(char* uplo,
+                       int* m,
+                       int* n,
+                       int* nrhs,
+                       double* a,
+                       int* lda,
+                       double* b,
+                       int* ldb,
+                       double* work,
+                       int* lwork,
+                       int* info);
+
+
+namespace ceres {
+namespace internal {
+
+int LAPACK::SolveInPlaceUsingCholesky(int num_rows,
+                                      const double* in_lhs,
+                                      double* rhs_and_solution) {
+#ifdef CERES_NO_LAPACK
+  LOG(FATAL) << "Ceres was built without a BLAS library.";
+  return -1;
+#else
+  char uplo = 'L';
+  int n = num_rows;
+  int info = 0;
+  int nrhs = 1;
+  double* lhs = const_cast<double*>(in_lhs);
+
+  dpotrf_(&uplo, &n, lhs, &n, &info);
+  if (info != 0) {
+    LOG(INFO) << "Cholesky factorization (dpotrf) failed: " << info;
+    return info;
+  }
+
+  dpotrs_(&uplo, &n, &nrhs, lhs, &n, rhs_and_solution, &n, &info);
+  if (info != 0) {
+    LOG(INFO) << "Triangular solve (dpotrs) failed: " << info;
+  }
+
+  return info;
+#endif
+};
+
+int LAPACK::EstimateWorkSizeForQR(int num_rows, int num_cols) {
+#ifdef CERES_NO_LAPACK
+  LOG(FATAL) << "Ceres was built without a LAPACK library.";
+  return -1;
+#else
+  char trans = 'N';
+  int nrhs = 1;
+  int lwork = -1;
+  double work;
+  int info = 0;
+  dgels_(&trans, &num_rows, &num_cols, &nrhs, NULL, &num_rows, NULL, &num_rows, &work, &lwork, &info);
+  CHECK_EQ(info, 0);
+  return work;
+#endif
+};
+
+int LAPACK::SolveUsingQR(int num_rows,
+                         int num_cols,
+                         const double* in_lhs,
+                         int work_size,
+                         double* work,
+                         double* rhs_and_solution) {
+#ifdef CERES_NO_LAPACK
+  LOG(FATAL) << "Ceres was built without a LAPACK library.";
+  return -1;
+#else
+  char trans = 'N';
+  int m = num_rows;
+  int n = num_cols;
+  int nrhs = 1;
+  int lda = num_rows;
+  int ldb = num_rows;
+  int info = 0;
+  double* lhs = const_cast<double*>(in_lhs);
+
+  dgels_(&trans, &m, &n, &nrhs, lhs, &lda, rhs_and_solution, &ldb, work, &work_size, &info);
+  return info;
+#endif
+};
+
+}  // namespace internal
+}  // namespace ceres