diff --git a/internal/ceres/program.cc b/internal/ceres/program.cc
new file mode 100644
index 0000000..f1cd1bb
--- /dev/null
+++ b/internal/ceres/program.cc
@@ -0,0 +1,526 @@
+// 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)
+
+#include "ceres/program.h"
+
+#include <algorithm>
+#include <map>
+#include <memory>
+#include <vector>
+
+#include "ceres/array_utils.h"
+#include "ceres/casts.h"
+#include "ceres/compressed_row_sparse_matrix.h"
+#include "ceres/cost_function.h"
+#include "ceres/evaluator.h"
+#include "ceres/internal/port.h"
+#include "ceres/local_parameterization.h"
+#include "ceres/loss_function.h"
+#include "ceres/map_util.h"
+#include "ceres/parameter_block.h"
+#include "ceres/problem.h"
+#include "ceres/residual_block.h"
+#include "ceres/stl_util.h"
+#include "ceres/triplet_sparse_matrix.h"
+
+namespace ceres {
+namespace internal {
+
+using std::max;
+using std::set;
+using std::string;
+using std::vector;
+
+Program::Program() {}
+
+Program::Program(const Program& program)
+    : parameter_blocks_(program.parameter_blocks_),
+      residual_blocks_(program.residual_blocks_) {
+}
+
+const vector<ParameterBlock*>& Program::parameter_blocks() const {
+  return parameter_blocks_;
+}
+
+const vector<ResidualBlock*>& Program::residual_blocks() const {
+  return residual_blocks_;
+}
+
+vector<ParameterBlock*>* Program::mutable_parameter_blocks() {
+  return &parameter_blocks_;
+}
+
+vector<ResidualBlock*>* Program::mutable_residual_blocks() {
+  return &residual_blocks_;
+}
+
+bool Program::StateVectorToParameterBlocks(const double *state) {
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    if (!parameter_blocks_[i]->IsConstant() &&
+        !parameter_blocks_[i]->SetState(state)) {
+      return false;
+    }
+    state += parameter_blocks_[i]->Size();
+  }
+  return true;
+}
+
+void Program::ParameterBlocksToStateVector(double *state) const {
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    parameter_blocks_[i]->GetState(state);
+    state += parameter_blocks_[i]->Size();
+  }
+}
+
+void Program::CopyParameterBlockStateToUserState() {
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    parameter_blocks_[i]->GetState(parameter_blocks_[i]->mutable_user_state());
+  }
+}
+
+bool Program::SetParameterBlockStatePtrsToUserStatePtrs() {
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    if (!parameter_blocks_[i]->IsConstant() &&
+        !parameter_blocks_[i]->SetState(parameter_blocks_[i]->user_state())) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool Program::Plus(const double* state,
+                   const double* delta,
+                   double* state_plus_delta) const {
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    if (!parameter_blocks_[i]->Plus(state, delta, state_plus_delta)) {
+      return false;
+    }
+    state += parameter_blocks_[i]->Size();
+    delta += parameter_blocks_[i]->LocalSize();
+    state_plus_delta += parameter_blocks_[i]->Size();
+  }
+  return true;
+}
+
+void Program::SetParameterOffsetsAndIndex() {
+  // Set positions for all parameters appearing as arguments to residuals to one
+  // past the end of the parameter block array.
+  for (int i = 0; i < residual_blocks_.size(); ++i) {
+    ResidualBlock* residual_block = residual_blocks_[i];
+    for (int j = 0; j < residual_block->NumParameterBlocks(); ++j) {
+      residual_block->parameter_blocks()[j]->set_index(-1);
+    }
+  }
+  // For parameters that appear in the program, set their position and offset.
+  int state_offset = 0;
+  int delta_offset = 0;
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    parameter_blocks_[i]->set_index(i);
+    parameter_blocks_[i]->set_state_offset(state_offset);
+    parameter_blocks_[i]->set_delta_offset(delta_offset);
+    state_offset += parameter_blocks_[i]->Size();
+    delta_offset += parameter_blocks_[i]->LocalSize();
+  }
+}
+
+bool Program::IsValid() const {
+  for (int i = 0; i < residual_blocks_.size(); ++i) {
+    const ResidualBlock* residual_block = residual_blocks_[i];
+    if (residual_block->index() != i) {
+      LOG(WARNING) << "Residual block: " << i
+                   << " has incorrect index: " << residual_block->index();
+      return false;
+    }
+  }
+
+  int state_offset = 0;
+  int delta_offset = 0;
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    const ParameterBlock* parameter_block = parameter_blocks_[i];
+    if (parameter_block->index() != i ||
+        parameter_block->state_offset() != state_offset ||
+        parameter_block->delta_offset() != delta_offset) {
+      LOG(WARNING) << "Parameter block: " << i
+                   << "has incorrect indexing information: "
+                   << parameter_block->ToString();
+      return false;
+    }
+
+    state_offset += parameter_blocks_[i]->Size();
+    delta_offset += parameter_blocks_[i]->LocalSize();
+  }
+
+  return true;
+}
+
+bool Program::ParameterBlocksAreFinite(string* message) const {
+  CHECK(message != nullptr);
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    const ParameterBlock* parameter_block = parameter_blocks_[i];
+    const double* array = parameter_block->user_state();
+    const int size = parameter_block->Size();
+    const int invalid_index = FindInvalidValue(size, array);
+    if (invalid_index != size) {
+      *message = StringPrintf(
+          "ParameterBlock: %p with size %d has at least one invalid value.\n"
+          "First invalid value is at index: %d.\n"
+          "Parameter block values: ",
+          array, size, invalid_index);
+      AppendArrayToString(size, array, message);
+      return false;
+    }
+  }
+  return true;
+}
+
+bool Program::IsBoundsConstrained() const {
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    const ParameterBlock* parameter_block = parameter_blocks_[i];
+    if (parameter_block->IsConstant()) {
+      continue;
+    }
+    const int size = parameter_block->Size();
+    for (int j = 0; j < size; ++j) {
+      const double lower_bound = parameter_block->LowerBoundForParameter(j);
+      const double upper_bound = parameter_block->UpperBoundForParameter(j);
+      if (lower_bound > -std::numeric_limits<double>::max() ||
+          upper_bound < std::numeric_limits<double>::max()) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+bool Program::IsFeasible(string* message) const {
+  CHECK(message != nullptr);
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    const ParameterBlock* parameter_block = parameter_blocks_[i];
+    const double* parameters = parameter_block->user_state();
+    const int size = parameter_block->Size();
+    if (parameter_block->IsConstant()) {
+      // Constant parameter blocks must start in the feasible region
+      // to ultimately produce a feasible solution, since Ceres cannot
+      // change them.
+      for (int j = 0; j < size; ++j) {
+        const double lower_bound = parameter_block->LowerBoundForParameter(j);
+        const double upper_bound = parameter_block->UpperBoundForParameter(j);
+        if (parameters[j] < lower_bound || parameters[j] > upper_bound) {
+          *message = StringPrintf(
+              "ParameterBlock: %p with size %d has at least one infeasible "
+              "value."
+              "\nFirst infeasible value is at index: %d."
+              "\nLower bound: %e, value: %e, upper bound: %e"
+              "\nParameter block values: ",
+              parameters, size, j, lower_bound, parameters[j], upper_bound);
+          AppendArrayToString(size, parameters, message);
+          return false;
+        }
+      }
+    } else {
+      // Variable parameter blocks must have non-empty feasible
+      // regions, otherwise there is no way to produce a feasible
+      // solution.
+      for (int j = 0; j < size; ++j) {
+        const double lower_bound = parameter_block->LowerBoundForParameter(j);
+        const double upper_bound = parameter_block->UpperBoundForParameter(j);
+        if (lower_bound >= upper_bound) {
+          *message = StringPrintf(
+              "ParameterBlock: %p with size %d has at least one infeasible "
+              "bound."
+              "\nFirst infeasible bound is at index: %d."
+              "\nLower bound: %e, upper bound: %e"
+              "\nParameter block values: ",
+              parameters, size, j, lower_bound, upper_bound);
+          AppendArrayToString(size, parameters, message);
+          return false;
+        }
+      }
+    }
+  }
+
+  return true;
+}
+
+Program* Program::CreateReducedProgram(
+    vector<double*>* removed_parameter_blocks,
+    double* fixed_cost,
+    string* error) const {
+  CHECK(removed_parameter_blocks != nullptr);
+  CHECK(fixed_cost != nullptr);
+  CHECK(error != nullptr);
+
+  std::unique_ptr<Program> reduced_program(new Program(*this));
+  if (!reduced_program->RemoveFixedBlocks(removed_parameter_blocks,
+                                          fixed_cost,
+                                          error)) {
+    return NULL;
+  }
+
+  reduced_program->SetParameterOffsetsAndIndex();
+  return reduced_program.release();
+}
+
+bool Program::RemoveFixedBlocks(vector<double*>* removed_parameter_blocks,
+                                double* fixed_cost,
+                                string* error) {
+  CHECK(removed_parameter_blocks != nullptr);
+  CHECK(fixed_cost != nullptr);
+  CHECK(error != nullptr);
+
+  std::unique_ptr<double[]> residual_block_evaluate_scratch;
+  residual_block_evaluate_scratch.reset(
+      new double[MaxScratchDoublesNeededForEvaluate()]);
+  *fixed_cost = 0.0;
+
+  // Mark all the parameters as unused. Abuse the index member of the
+  // parameter blocks for the marking.
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    parameter_blocks_[i]->set_index(-1);
+  }
+
+  // Filter out residual that have all-constant parameters, and mark
+  // all the parameter blocks that appear in residuals.
+  int num_active_residual_blocks = 0;
+  for (int i = 0; i < residual_blocks_.size(); ++i) {
+    ResidualBlock* residual_block = residual_blocks_[i];
+    int num_parameter_blocks = residual_block->NumParameterBlocks();
+
+    // Determine if the residual block is fixed, and also mark varying
+    // parameters that appear in the residual block.
+    bool all_constant = true;
+    for (int k = 0; k < num_parameter_blocks; k++) {
+      ParameterBlock* parameter_block = residual_block->parameter_blocks()[k];
+      if (!parameter_block->IsConstant()) {
+        all_constant = false;
+        parameter_block->set_index(1);
+      }
+    }
+
+    if (!all_constant) {
+      residual_blocks_[num_active_residual_blocks++] = residual_block;
+      continue;
+    }
+
+    // The residual is constant and will be removed, so its cost is
+    // added to the variable fixed_cost.
+    double cost = 0.0;
+    if (!residual_block->Evaluate(true,
+                                  &cost,
+                                  NULL,
+                                  NULL,
+                                  residual_block_evaluate_scratch.get())) {
+      *error = StringPrintf("Evaluation of the residual %d failed during "
+                            "removal of fixed residual blocks.", i);
+      return false;
+    }
+    *fixed_cost += cost;
+  }
+  residual_blocks_.resize(num_active_residual_blocks);
+
+  // Filter out unused or fixed parameter blocks.
+  int num_active_parameter_blocks = 0;
+  removed_parameter_blocks->clear();
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    ParameterBlock* parameter_block = parameter_blocks_[i];
+    if (parameter_block->index() == -1) {
+      removed_parameter_blocks->push_back(
+          parameter_block->mutable_user_state());
+    } else {
+      parameter_blocks_[num_active_parameter_blocks++] = parameter_block;
+    }
+  }
+  parameter_blocks_.resize(num_active_parameter_blocks);
+
+  if (!(((NumResidualBlocks() == 0) &&
+         (NumParameterBlocks() == 0)) ||
+        ((NumResidualBlocks() != 0) &&
+         (NumParameterBlocks() != 0)))) {
+    *error =  "Congratulations, you found a bug in Ceres. Please report it.";
+    return false;
+  }
+
+  return true;
+}
+
+bool Program::IsParameterBlockSetIndependent(
+    const set<double*>& independent_set) const {
+  // Loop over each residual block and ensure that no two parameter
+  // blocks in the same residual block are part of
+  // parameter_block_ptrs as that would violate the assumption that it
+  // is an independent set in the Hessian matrix.
+  for (const ResidualBlock* residual_block : residual_blocks_) {
+    ParameterBlock* const* parameter_blocks =
+        residual_block->parameter_blocks();
+    const int num_parameter_blocks = residual_block->NumParameterBlocks();
+    int count = 0;
+    for (int i = 0; i < num_parameter_blocks; ++i) {
+      count += independent_set.count(
+          parameter_blocks[i]->mutable_user_state());
+    }
+    if (count > 1) {
+      return false;
+    }
+  }
+  return true;
+}
+
+TripletSparseMatrix* Program::CreateJacobianBlockSparsityTranspose() const {
+  // Matrix to store the block sparsity structure of the Jacobian.
+  TripletSparseMatrix* tsm =
+      new TripletSparseMatrix(NumParameterBlocks(),
+                              NumResidualBlocks(),
+                              10 * NumResidualBlocks());
+  int num_nonzeros = 0;
+  int* rows = tsm->mutable_rows();
+  int* cols = tsm->mutable_cols();
+  double* values = tsm->mutable_values();
+
+  for (int c = 0; c < residual_blocks_.size(); ++c) {
+    const ResidualBlock* residual_block = residual_blocks_[c];
+    const int num_parameter_blocks = residual_block->NumParameterBlocks();
+    ParameterBlock* const* parameter_blocks =
+        residual_block->parameter_blocks();
+
+    for (int j = 0; j < num_parameter_blocks; ++j) {
+      if (parameter_blocks[j]->IsConstant()) {
+        continue;
+      }
+
+      // Re-size the matrix if needed.
+      if (num_nonzeros >= tsm->max_num_nonzeros()) {
+        tsm->set_num_nonzeros(num_nonzeros);
+        tsm->Reserve(2 * num_nonzeros);
+        rows = tsm->mutable_rows();
+        cols = tsm->mutable_cols();
+        values = tsm->mutable_values();
+      }
+
+      const int r = parameter_blocks[j]->index();
+      rows[num_nonzeros] = r;
+      cols[num_nonzeros] = c;
+      values[num_nonzeros] = 1.0;
+      ++num_nonzeros;
+    }
+  }
+
+  tsm->set_num_nonzeros(num_nonzeros);
+  return tsm;
+}
+
+int Program::NumResidualBlocks() const {
+  return residual_blocks_.size();
+}
+
+int Program::NumParameterBlocks() const {
+  return parameter_blocks_.size();
+}
+
+int Program::NumResiduals() const {
+  int num_residuals = 0;
+  for (int i = 0; i < residual_blocks_.size(); ++i) {
+    num_residuals += residual_blocks_[i]->NumResiduals();
+  }
+  return num_residuals;
+}
+
+int Program::NumParameters() const {
+  int num_parameters = 0;
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    num_parameters += parameter_blocks_[i]->Size();
+  }
+  return num_parameters;
+}
+
+int Program::NumEffectiveParameters() const {
+  int num_parameters = 0;
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    num_parameters += parameter_blocks_[i]->LocalSize();
+  }
+  return num_parameters;
+}
+
+int Program::MaxScratchDoublesNeededForEvaluate() const {
+  // Compute the scratch space needed for evaluate.
+  int max_scratch_bytes_for_evaluate = 0;
+  for (int i = 0; i < residual_blocks_.size(); ++i) {
+    max_scratch_bytes_for_evaluate =
+        max(max_scratch_bytes_for_evaluate,
+            residual_blocks_[i]->NumScratchDoublesForEvaluate());
+  }
+  return max_scratch_bytes_for_evaluate;
+}
+
+int Program::MaxDerivativesPerResidualBlock() const {
+  int max_derivatives = 0;
+  for (int i = 0; i < residual_blocks_.size(); ++i) {
+    int derivatives = 0;
+    ResidualBlock* residual_block = residual_blocks_[i];
+    int num_parameters = residual_block->NumParameterBlocks();
+    for (int j = 0; j < num_parameters; ++j) {
+      derivatives += residual_block->NumResiduals() *
+                     residual_block->parameter_blocks()[j]->LocalSize();
+    }
+    max_derivatives = max(max_derivatives, derivatives);
+  }
+  return max_derivatives;
+}
+
+int Program::MaxParametersPerResidualBlock() const {
+  int max_parameters = 0;
+  for (int i = 0; i < residual_blocks_.size(); ++i) {
+    max_parameters = max(max_parameters,
+                         residual_blocks_[i]->NumParameterBlocks());
+  }
+  return max_parameters;
+}
+
+int Program::MaxResidualsPerResidualBlock() const {
+  int max_residuals = 0;
+  for (int i = 0; i < residual_blocks_.size(); ++i) {
+    max_residuals = max(max_residuals, residual_blocks_[i]->NumResiduals());
+  }
+  return max_residuals;
+}
+
+string Program::ToString() const {
+  string ret = "Program dump\n";
+  ret += StringPrintf("Number of parameter blocks: %d\n", NumParameterBlocks());
+  ret += StringPrintf("Number of parameters: %d\n", NumParameters());
+  ret += "Parameters:\n";
+  for (int i = 0; i < parameter_blocks_.size(); ++i) {
+    ret += StringPrintf("%d: %s\n",
+                        i, parameter_blocks_[i]->ToString().c_str());
+  }
+  return ret;
+}
+
+}  // namespace internal
+}  // namespace ceres