diff --git a/internal/ceres/detect_structure.h b/internal/ceres/detect_structure.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: sameeragarwal@google.com (Sameer Agarwal)
+
+#ifndef CERES_INTERNAL_DETECT_STRUCTURE_H_
+#define CERES_INTERNAL_DETECT_STRUCTURE_H_
+
+#include "ceres/block_structure.h"
+
+namespace ceres {
+namespace internal {
+
+// Detect static blocks in the problem sparsity. For rows containing
+// e_blocks, we are interested in detecting if the size of the row
+// blocks, e_blocks and the f_blocks remain constant. If they do, then
+// we can use template specialization to improve the performance of
+// the block level linear algebra operations used by the
+// SchurEliminator.
+//
+// If a block size is not constant, we return Eigen::Dynamic as the
+// value. This just means that the eliminator uses dynamically sized
+// linear algebra operations rather than static operations whose size
+// is known as compile time.
+//
+// For more details about e_blocks and f_blocks, see
+// schur_eliminator.h. This information is used to initialized an
+// appropriate template specialization of SchurEliminator.
+//
+// Note: The structure of rows without any e-blocks has no effect on
+// the values returned by this function. It is entirely possible that
+// the f_block_size and row_blocks_size is not constant in such rows.
+void DetectStructure(const CompressedRowBlockStructure& bs,
+                     const int num_eliminate_blocks,
+                     int* row_block_size,
+                     int* e_block_size,
+                     int* f_block_size);
+
+}  // namespace internal
+}  // namespace ceres
+
+#endif  // CERES_INTERNAL_DETECT_STRUCTURE_H_