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diff --git a/internal/ceres/tiny_solver_test_util.h b/internal/ceres/tiny_solver_test_util.h
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+
+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2017 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: mierle@gmail.com (Keir Mierle)
+
+#ifndef CERES_INTERNAL_TINY_SOLVER_TEST_UTIL_H_
+#define CERES_INTERNAL_TINY_SOLVER_TEST_UTIL_H_
+
+namespace ceres {
+
+template<typename T>
+bool EvaluateResidualsAndJacobians(const T* parameters,
+                                   T* residuals,
+                                   T* jacobian) {
+  T x = parameters[0];
+  T y = parameters[1];
+  T z = parameters[2];
+
+  residuals[0] = x + static_cast<T>(2) * y + static_cast<T>(4) * z;
+  residuals[1] = y * z;
+
+  if (jacobian) {
+    jacobian[0 * 2 + 0] = static_cast<T>(1);
+    jacobian[0 * 2 + 1] = static_cast<T>(0);
+
+    jacobian[1 * 2 + 0] = static_cast<T>(2);
+    jacobian[1 * 2 + 1] = z;
+
+    jacobian[2 * 2 + 0] = static_cast<T>(4);
+    jacobian[2 * 2 + 1] = y;
+  }
+  return true;
+}
+
+}  // namespace ceres
+
+#endif  // CERES_INTERNAL_TINY_SOLVER_TEST_UTIL_H_