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// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2023 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
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// 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/detect_structure.h"
#include "absl/log/check.h"
#include "absl/log/log.h"
#include "ceres/internal/eigen.h"
namespace ceres::internal {
void DetectStructure(const CompressedRowBlockStructure& bs,
const int num_eliminate_blocks,
int* row_block_size,
int* e_block_size,
int* f_block_size) {
const int num_row_blocks = bs.rows.size();
*row_block_size = 0;
*e_block_size = 0;
*f_block_size = 0;
// Iterate over row blocks of the matrix, checking if row_block,
// e_block or f_block sizes remain constant.
for (int r = 0; r < num_row_blocks; ++r) {
const CompressedRow& row = bs.rows[r];
// We do not care about the sizes of the blocks in rows which do
// not contain e_blocks.
if (row.cells.front().block_id >= num_eliminate_blocks) {
break;
}
// Detect fixed or dynamic row block size.
if (*row_block_size == 0) {
*row_block_size = row.block.size;
} else if (*row_block_size != Eigen::Dynamic &&
*row_block_size != row.block.size) {
VLOG(2) << "Dynamic row block size because the block size changed from "
<< *row_block_size << " to " << row.block.size;
*row_block_size = Eigen::Dynamic;
}
// Detect fixed or dynamic e-block size.
const int e_block_id = row.cells.front().block_id;
if (*e_block_size == 0) {
*e_block_size = bs.cols[e_block_id].size;
} else if (*e_block_size != Eigen::Dynamic &&
*e_block_size != bs.cols[e_block_id].size) {
VLOG(2) << "Dynamic e block size because the block size changed from "
<< *e_block_size << " to " << bs.cols[e_block_id].size;
*e_block_size = Eigen::Dynamic;
}
// Detect fixed or dynamic f-block size. We are only interested in
// rows with e-blocks, and the e-block is always the first block,
// so only rows of size greater than 1 are of interest.
if (row.cells.size() > 1) {
if (*f_block_size == 0) {
const int f_block_id = row.cells[1].block_id;
*f_block_size = bs.cols[f_block_id].size;
}
for (int c = 1;
(c < row.cells.size()) && (*f_block_size != Eigen::Dynamic);
++c) {
const int f_block_id = row.cells[c].block_id;
if (*f_block_size != bs.cols[f_block_id].size) {
VLOG(2) << "Dynamic f block size because the block size "
<< "changed from " << *f_block_size << " to "
<< bs.cols[f_block_id].size;
*f_block_size = Eigen::Dynamic;
}
}
}
// clang-format off
const bool is_everything_dynamic = (*row_block_size == Eigen::Dynamic &&
*e_block_size == Eigen::Dynamic &&
*f_block_size == Eigen::Dynamic);
// clang-format on
if (is_everything_dynamic) {
break;
}
}
CHECK_NE(*row_block_size, 0) << "No rows found";
CHECK_NE(*e_block_size, 0) << "No e type blocks found";
// clang-format off
VLOG(1) << "Schur complement static structure <"
<< *row_block_size << ","
<< *e_block_size << ","
<< *f_block_size << ">.";
// clang-format on
}
} // namespace ceres::internal