diff --git a/internal/ceres/program.h b/internal/ceres/program.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: keir@google.com (Keir Mierle)
+
+#ifndef CERES_INTERNAL_PROGRAM_H_
+#define CERES_INTERNAL_PROGRAM_H_
+
+#include <set>
+#include <string>
+#include <vector>
+#include "ceres/internal/port.h"
+
+namespace ceres {
+namespace internal {
+
+class ParameterBlock;
+class ProblemImpl;
+class ResidualBlock;
+class TripletSparseMatrix;
+
+// A nonlinear least squares optimization problem. This is different from the
+// similarly-named "Problem" object, which offers a mutation interface for
+// adding and modifying parameters and residuals. The Program contains the core
+// part of the Problem, which is the parameters and the residuals, stored in a
+// particular ordering. The ordering is critical, since it defines the mapping
+// between (residual, parameter) pairs and a position in the jacobian of the
+// objective function. Various parts of Ceres transform one Program into
+// another; for example, the first stage of solving involves stripping all
+// constant parameters and residuals. This is in contrast with Problem, which is
+// not built for transformation.
+class Program {
+ public:
+  Program();
+  explicit Program(const Program& program);
+
+  // The ordered parameter and residual blocks for the program.
+  const std::vector<ParameterBlock*>& parameter_blocks() const;
+  const std::vector<ResidualBlock*>& residual_blocks() const;
+  std::vector<ParameterBlock*>* mutable_parameter_blocks();
+  std::vector<ResidualBlock*>* mutable_residual_blocks();
+
+  // Serialize to/from the program and update states.
+  //
+  // NOTE: Setting the state of a parameter block can trigger the
+  // computation of the Jacobian of its local parameterization. If
+  // this computation fails for some reason, then this method returns
+  // false and the state of the parameter blocks cannot be trusted.
+  bool StateVectorToParameterBlocks(const double *state);
+  void ParameterBlocksToStateVector(double *state) const;
+
+  // Copy internal state to the user's parameters.
+  void CopyParameterBlockStateToUserState();
+
+  // Set the parameter block pointers to the user pointers. Since this
+  // runs parameter block set state internally, which may call local
+  // parameterizations, this can fail. False is returned on failure.
+  bool SetParameterBlockStatePtrsToUserStatePtrs();
+
+  // Update a state vector for the program given a delta.
+  bool Plus(const double* state,
+            const double* delta,
+            double* state_plus_delta) const;
+
+  // Set the parameter indices and offsets. This permits mapping backward
+  // from a ParameterBlock* to an index in the parameter_blocks() vector. For
+  // any parameter block p, after calling SetParameterOffsetsAndIndex(), it
+  // is true that
+  //
+  //   parameter_blocks()[p->index()] == p
+  //
+  // If a parameter appears in a residual but not in the parameter block, then
+  // it will have an index of -1.
+  //
+  // This also updates p->state_offset() and p->delta_offset(), which are the
+  // position of the parameter in the state and delta vector respectively.
+  void SetParameterOffsetsAndIndex();
+
+  // Check if the internal state of the program (the indexing and the
+  // offsets) are correct.
+  bool IsValid() const;
+
+  bool ParameterBlocksAreFinite(std::string* message) const;
+
+  // Returns true if the program has any non-constant parameter blocks
+  // which have non-trivial bounds constraints.
+  bool IsBoundsConstrained() const;
+
+  // Returns false, if the program has any constant parameter blocks
+  // which are not feasible, or any variable parameter blocks which
+  // have a lower bound greater than or equal to the upper bound.
+  bool IsFeasible(std::string* message) const;
+
+  // Loop over each residual block and ensure that no two parameter
+  // blocks in the same residual block are part of
+  // parameter_blocks as that would violate the assumption that it
+  // is an independent set in the Hessian matrix.
+  bool IsParameterBlockSetIndependent(
+      const std::set<double*>& independent_set) const;
+
+  // Create a TripletSparseMatrix which contains the zero-one
+  // structure corresponding to the block sparsity of the transpose of
+  // the Jacobian matrix.
+  //
+  // Caller owns the result.
+  TripletSparseMatrix* CreateJacobianBlockSparsityTranspose() const;
+
+  // Create a copy of this program and removes constant parameter
+  // blocks and residual blocks with no varying parameter blocks while
+  // preserving their relative order.
+  //
+  // removed_parameter_blocks on exit will contain the list of
+  // parameter blocks that were removed.
+  //
+  // fixed_cost will be equal to the sum of the costs of the residual
+  // blocks that were removed.
+  //
+  // If there was a problem, then the function will return a NULL
+  // pointer and error will contain a human readable description of
+  // the problem.
+  Program* CreateReducedProgram(std::vector<double*>* removed_parameter_blocks,
+                                double* fixed_cost,
+                                std::string* error) const;
+
+  // See problem.h for what these do.
+  int NumParameterBlocks() const;
+  int NumParameters() const;
+  int NumEffectiveParameters() const;
+  int NumResidualBlocks() const;
+  int NumResiduals() const;
+
+  int MaxScratchDoublesNeededForEvaluate() const;
+  int MaxDerivativesPerResidualBlock() const;
+  int MaxParametersPerResidualBlock() const;
+  int MaxResidualsPerResidualBlock() const;
+
+  // A human-readable dump of the parameter blocks for debugging.
+  // TODO(keir): If necessary, also dump the residual blocks.
+  std::string ToString() const;
+
+ private:
+  // Remove constant parameter blocks and residual blocks with no
+  // varying parameter blocks while preserving their relative order.
+  //
+  // removed_parameter_blocks on exit will contain the list of
+  // parameter blocks that were removed.
+  //
+  // fixed_cost will be equal to the sum of the costs of the residual
+  // blocks that were removed.
+  //
+  // If there was a problem, then the function will return false and
+  // error will contain a human readable description of the problem.
+  bool RemoveFixedBlocks(std::vector<double*>* removed_parameter_blocks,
+                         double* fixed_cost,
+                         std::string* message);
+
+  // The Program does not own the ParameterBlock or ResidualBlock objects.
+  std::vector<ParameterBlock*> parameter_blocks_;
+  std::vector<ResidualBlock*> residual_blocks_;
+
+  friend class ProblemImpl;
+};
+
+}  // namespace internal
+}  // namespace ceres
+
+#endif  // CERES_INTERNAL_PROGRAM_H_