diff --git a/internal/ceres/gradient_problem.cc b/internal/ceres/gradient_problem.cc
new file mode 100644
index 0000000..4ebd3e6
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+++ b/internal/ceres/gradient_problem.cc
@@ -0,0 +1,81 @@
+// 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)
+
+#include "ceres/gradient_problem.h"
+#include "ceres/local_parameterization.h"
+#include "glog/logging.h"
+
+namespace ceres {
+
+GradientProblem::GradientProblem(FirstOrderFunction* function)
+    : function_(function),
+      parameterization_(
+          new IdentityParameterization(function_->NumParameters())),
+      scratch_(new double[function_->NumParameters()]) {
+}
+
+GradientProblem::GradientProblem(FirstOrderFunction* function,
+                                 LocalParameterization* parameterization)
+      : function_(function),
+        parameterization_(parameterization),
+        scratch_(new double[function_->NumParameters()]) {
+  CHECK_EQ(function_->NumParameters(), parameterization_->GlobalSize());
+}
+
+int GradientProblem::NumParameters() const {
+  return function_->NumParameters();
+}
+
+int GradientProblem::NumLocalParameters() const {
+  return parameterization_->LocalSize();
+}
+
+
+bool GradientProblem::Evaluate(const double* parameters,
+                               double* cost,
+                               double* gradient) const {
+  if (gradient == NULL) {
+    return function_->Evaluate(parameters, cost, NULL);
+  }
+
+  return (function_->Evaluate(parameters, cost, scratch_.get()) &&
+          parameterization_->MultiplyByJacobian(parameters,
+                                                1,
+                                                scratch_.get(),
+                                                gradient));
+}
+
+bool GradientProblem::Plus(const double* x,
+                           const double* delta,
+                           double* x_plus_delta) const {
+  return parameterization_->Plus(x, delta, x_plus_delta);
+}
+
+}  // namespace ceres