diff --git a/internal/ceres/line_search_direction.h b/internal/ceres/line_search_direction.h
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+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2012 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)
+
+#ifndef CERES_INTERNAL_LINE_SEARCH_DIRECTION_H_
+#define CERES_INTERNAL_LINE_SEARCH_DIRECTION_H_
+
+#include "ceres/internal/eigen.h"
+#include "ceres/line_search_minimizer.h"
+#include "ceres/types.h"
+
+namespace ceres {
+namespace internal {
+
+class LineSearchDirection {
+ public:
+  struct Options {
+    Options()
+        : num_parameters(0),
+          type(LBFGS),
+          nonlinear_conjugate_gradient_type(FLETCHER_REEVES),
+          function_tolerance(1e-12),
+          max_lbfgs_rank(20) {
+    }
+
+    int num_parameters;
+    LineSearchDirectionType type;
+    NonlinearConjugateGradientType nonlinear_conjugate_gradient_type;
+    double function_tolerance;
+    int max_lbfgs_rank;
+  };
+
+  static LineSearchDirection* Create(Options& options);
+
+  virtual ~LineSearchDirection() {}
+  virtual bool NextDirection(const LineSearchMinimizer::State& previous,
+                             const LineSearchMinimizer::State& current,
+                             Vector* search_direction) = 0;
+
+};
+
+}  // namespace internal
+}  // namespace ceres
+
+#endif // CERES_INTERNAL_LINE_SEARCH_DIRECTION_H_